Discern between virtual and abstract class bindings

* Previous "virtual" classes (which can't be instantiated) are not corretly named "abstract".
* Added a new "virtual" category for classes, they can't be instantiated from the editor, but can be inherited from script and extensions.
* Converted a large amount of classes from "abstract" to "virtual" where it makes sense.

Most classes that make sense have been converted. Missing:

* Physics servers
* VideoStream
* Script* classes.

which will go in a separate PR due to the complexity involved.

13 files changed, 315 insertions, 1 deletions

diff --git a/doc/classes/AudioEffect.xml b/doc/classes/AudioEffect.xml
index 424669eab9..5bfa5be0ca 100644
--- a/doc/classes/AudioEffect.xml
+++ b/doc/classes/AudioEffect.xml
@@ -9,4 +9,11 @@
 	<tutorials>
 		<link title="Audio Mic Record Demo">https://godotengine.org/asset-library/asset/527</link>
 	</tutorials>
+	<methods>
+		<method name="_instantiate" qualifiers="virtual">
+			<return type="AudioEffectInstance" />
+			<description>
+			</description>
+		</method>
+	</methods>
 </class>
diff --git a/doc/classes/AudioEffectInstance.xml b/doc/classes/AudioEffectInstance.xml
index 369b4130d4..f50246d6ca 100644
--- a/doc/classes/AudioEffectInstance.xml
+++ b/doc/classes/AudioEffectInstance.xml
@@ -6,4 +6,19 @@
 	</description>
 	<tutorials>
 	</tutorials>
+	<methods>
+		<method name="_process" qualifiers="virtual">
+			<return type="void" />
+			<argument index="0" name="src_buffer" type="const void*" />
+			<argument index="1" name="dst_buffer" type="AudioFrame*" />
+			<argument index="2" name="frame_count" type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_process_silence" qualifiers="virtual const">
+			<return type="bool" />
+			<description>
+			</description>
+		</method>
+	</methods>
 </class>
diff --git a/doc/classes/AudioStreamPlaybackResampled.xml b/doc/classes/AudioStreamPlaybackResampled.xml
index 228b8c19c0..eb41e4256e 100644
--- a/doc/classes/AudioStreamPlaybackResampled.xml
+++ b/doc/classes/AudioStreamPlaybackResampled.xml
@@ -6,4 +6,23 @@
 	</description>
 	<tutorials>
 	</tutorials>
+	<methods>
+		<method name="_get_stream_sampling_rate" qualifiers="virtual const">
+			<return type="float" />
+			<description>
+			</description>
+		</method>
+		<method name="_mix_resampled" qualifiers="virtual">
+			<return type="int" />
+			<argument index="0" name="dst_buffer" type="AudioFrame*" />
+			<argument index="1" name="frame_count" type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="begin_resample">
+			<return type="void" />
+			<description>
+			</description>
+		</method>
+	</methods>
 </class>
diff --git a/doc/classes/Material.xml b/doc/classes/Material.xml
index 78dbf8729b..c5d567c1fe 100644
--- a/doc/classes/Material.xml
+++ b/doc/classes/Material.xml
@@ -11,6 +11,26 @@
 		<link title="Third Person Shooter Demo">https://godotengine.org/asset-library/asset/678</link>
 	</tutorials>
 	<methods>
+		<method name="_can_do_next_pass" qualifiers="virtual const">
+			<return type="bool" />
+			<description>
+			</description>
+		</method>
+		<method name="_can_use_render_priority" qualifiers="virtual const">
+			<return type="bool" />
+			<description>
+			</description>
+		</method>
+		<method name="_get_shader_mode" qualifiers="virtual const">
+			<return type="int" enum="Shader.Mode" />
+			<description>
+			</description>
+		</method>
+		<method name="_get_shader_rid" qualifiers="virtual const">
+			<return type="RID" />
+			<description>
+			</description>
+		</method>
 		<method name="inspect_native_shader_code">
 			<return type="void" />
 			<description>
@@ -22,7 +42,7 @@
 			Sets the [Material] to be used for the next pass. This renders the object again using a different material.
 			[b]Note:[/b] This only applies to [StandardMaterial3D]s and [ShaderMaterial]s with type "Spatial".
 		</member>
-		<member name="render_priority" type="int" setter="set_render_priority" getter="get_render_priority" default="0">
+		<member name="render_priority" type="int" setter="set_render_priority" getter="get_render_priority">
 			Sets the render priority for transparent objects in 3D scenes. Higher priority objects will be sorted in front of lower priority objects.
 			[b]Note:[/b] This only applies to [StandardMaterial3D]s and [ShaderMaterial]s with type "Spatial".
 			[b]Note:[/b] This only applies to sorting of transparent objects. This will not impact how transparent objects are sorted relative to opaque objects. This is because opaque objects are not sorted, while transparent objects are sorted from back to front (subject to priority).
diff --git a/doc/classes/Mesh.xml b/doc/classes/Mesh.xml
index c5bfdcecd2..e4116cddfe 100644
--- a/doc/classes/Mesh.xml
+++ b/doc/classes/Mesh.xml
@@ -13,6 +13,89 @@
 		<link title="Third Person Shooter Demo">https://godotengine.org/asset-library/asset/678</link>
 	</tutorials>
 	<methods>
+		<method name="_get_aabb" qualifiers="virtual const">
+			<return type="AABB" />
+			<description>
+			</description>
+		</method>
+		<method name="_get_blend_shape_count" qualifiers="virtual const">
+			<return type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_get_blend_shape_name" qualifiers="virtual const">
+			<return type="StringName" />
+			<argument index="0" name="index" type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_get_surface_count" qualifiers="virtual const">
+			<return type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_set_blend_shape_name" qualifiers="virtual">
+			<return type="void" />
+			<argument index="0" name="index" type="int" />
+			<argument index="1" name="name" type="StringName" />
+			<description>
+			</description>
+		</method>
+		<method name="_surface_get_array_index_len" qualifiers="virtual const">
+			<return type="int" />
+			<argument index="0" name="index" type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_surface_get_array_len" qualifiers="virtual const">
+			<return type="int" />
+			<argument index="0" name="index" type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_surface_get_arrays" qualifiers="virtual const">
+			<return type="Array" />
+			<argument index="0" name="index" type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_surface_get_blend_shape_arrays" qualifiers="virtual const">
+			<return type="Array" />
+			<argument index="0" name="index" type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_surface_get_format" qualifiers="virtual const">
+			<return type="int" />
+			<argument index="0" name="index" type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_surface_get_lods" qualifiers="virtual const">
+			<return type="Dictionary" />
+			<argument index="0" name="index" type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_surface_get_material" qualifiers="virtual const">
+			<return type="Material" />
+			<argument index="0" name="index" type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_surface_get_primitive_type" qualifiers="virtual const">
+			<return type="int" />
+			<argument index="0" name="index" type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_surface_set_material" qualifiers="virtual">
+			<return type="void" />
+			<argument index="0" name="index" type="int" />
+			<argument index="1" name="material" type="Material" />
+			<description>
+			</description>
+		</method>
 		<method name="create_convex_shape" qualifiers="const">
 			<return type="Shape3D" />
 			<argument index="0" name="clean" type="bool" default="true" />
diff --git a/doc/classes/PrimitiveMesh.xml b/doc/classes/PrimitiveMesh.xml
index d0136e389a..329d81342b 100644
--- a/doc/classes/PrimitiveMesh.xml
+++ b/doc/classes/PrimitiveMesh.xml
@@ -9,6 +9,11 @@
 	<tutorials>
 	</tutorials>
 	<methods>
+		<method name="_create_mesh_array" qualifiers="virtual const">
+			<return type="Array" />
+			<description>
+			</description>
+		</method>
 		<method name="get_mesh_arrays" qualifiers="const">
 			<return type="Array" />
 			<description>
diff --git a/doc/classes/Range.xml b/doc/classes/Range.xml
index 70a9912b76..c150198eb1 100644
--- a/doc/classes/Range.xml
+++ b/doc/classes/Range.xml
@@ -9,6 +9,12 @@
 	<tutorials>
 	</tutorials>
 	<methods>
+		<method name="_value_changed" qualifiers="virtual">
+			<return type="void" />
+			<argument index="0" name="" type="float" />
+			<description>
+			</description>
+		</method>
 		<method name="share">
 			<return type="void" />
 			<argument index="0" name="with" type="Node" />
diff --git a/doc/classes/Resource.xml b/doc/classes/Resource.xml
index 0850d39015..b08b1540ab 100644
--- a/doc/classes/Resource.xml
+++ b/doc/classes/Resource.xml
@@ -12,6 +12,11 @@
 		<link title="When and how to avoid using nodes for everything">$DOCS_URL/tutorials/best_practices/node_alternatives.html</link>
 	</tutorials>
 	<methods>
+		<method name="_get_rid" qualifiers="virtual">
+			<return type="RID" />
+			<description>
+			</description>
+		</method>
 		<method name="duplicate" qualifiers="const">
 			<return type="Resource" />
 			<argument index="0" name="subresources" type="bool" default="false" />
diff --git a/doc/classes/StyleBox.xml b/doc/classes/StyleBox.xml
index f805692f4d..bc2333f26a 100644
--- a/doc/classes/StyleBox.xml
+++ b/doc/classes/StyleBox.xml
@@ -10,6 +10,37 @@
 	<tutorials>
 	</tutorials>
 	<methods>
+		<method name="_draw" qualifiers="virtual const">
+			<return type="void" />
+			<argument index="0" name="to_canvas_item" type="RID" />
+			<argument index="1" name="rect" type="Rect2" />
+			<description>
+			</description>
+		</method>
+		<method name="_get_center_size" qualifiers="virtual const">
+			<return type="Vector2" />
+			<description>
+			</description>
+		</method>
+		<method name="_get_draw_rect" qualifiers="virtual const">
+			<return type="Rect2" />
+			<argument index="0" name="rect" type="Rect2" />
+			<description>
+			</description>
+		</method>
+		<method name="_get_style_margin" qualifiers="virtual const">
+			<return type="float" />
+			<argument index="0" name="side" type="int" enum="Side" />
+			<description>
+			</description>
+		</method>
+		<method name="_test_mask" qualifiers="virtual const">
+			<return type="bool" />
+			<argument index="0" name="point" type="Vector2" />
+			<argument index="1" name="rect" type="Rect2" />
+			<description>
+			</description>
+		</method>
 		<method name="draw" qualifiers="const">
 			<return type="void" />
 			<argument index="0" name="canvas_item" type="RID" />
diff --git a/doc/classes/Texture2D.xml b/doc/classes/Texture2D.xml
index de9bbb4b3d..1bbebe085e 100644
--- a/doc/classes/Texture2D.xml
+++ b/doc/classes/Texture2D.xml
@@ -12,6 +12,58 @@
 	<tutorials>
 	</tutorials>
 	<methods>
+		<method name="_draw" qualifiers="virtual const">
+			<return type="void" />
+			<argument index="0" name="to_canvas_item" type="RID" />
+			<argument index="1" name="pos" type="Vector2" />
+			<argument index="2" name="modulate" type="Color" />
+			<argument index="3" name="transpose" type="bool" />
+			<description>
+			</description>
+		</method>
+		<method name="_draw_rect" qualifiers="virtual const">
+			<return type="void" />
+			<argument index="0" name="to_canvas_item" type="RID" />
+			<argument index="1" name="rect" type="Rect2" />
+			<argument index="2" name="tile" type="bool" />
+			<argument index="3" name="modulate" type="Color" />
+			<argument index="4" name="transpose" type="bool" />
+			<description>
+			</description>
+		</method>
+		<method name="_draw_rect_region" qualifiers="virtual const">
+			<return type="void" />
+			<argument index="0" name="tp_canvas_item" type="RID" />
+			<argument index="1" name="rect" type="Rect2" />
+			<argument index="2" name="src_rect" type="Rect2" />
+			<argument index="3" name="modulate" type="Color" />
+			<argument index="4" name="transpose" type="bool" />
+			<argument index="5" name="clip_uv" type="bool" />
+			<description>
+			</description>
+		</method>
+		<method name="_get_height" qualifiers="virtual const">
+			<return type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_get_width" qualifiers="virtual const">
+			<return type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_has_alpha" qualifiers="virtual const">
+			<return type="bool" />
+			<description>
+			</description>
+		</method>
+		<method name="_is_pixel_opaque" qualifiers="virtual const">
+			<return type="bool" />
+			<argument index="0" name="x" type="int" />
+			<argument index="1" name="y" type="int" />
+			<description>
+			</description>
+		</method>
 		<method name="draw" qualifiers="const">
 			<return type="void" />
 			<argument index="0" name="canvas_item" type="RID" />
diff --git a/doc/classes/Texture3D.xml b/doc/classes/Texture3D.xml
index bdfa428328..4968f46fe8 100644
--- a/doc/classes/Texture3D.xml
+++ b/doc/classes/Texture3D.xml
@@ -7,6 +7,36 @@
 	<tutorials>
 	</tutorials>
 	<methods>
+		<method name="_get_data" qualifiers="virtual const">
+			<return type="Image[]" />
+			<description>
+			</description>
+		</method>
+		<method name="_get_depth" qualifiers="virtual const">
+			<return type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_get_format" qualifiers="virtual const">
+			<return type="int" enum="Image.Format" />
+			<description>
+			</description>
+		</method>
+		<method name="_get_height" qualifiers="virtual const">
+			<return type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_get_width" qualifiers="virtual const">
+			<return type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_has_mipmaps" qualifiers="virtual const">
+			<return type="bool" />
+			<description>
+			</description>
+		</method>
 		<method name="get_data" qualifiers="const">
 			<return type="Image[]" />
 			<description>
diff --git a/doc/classes/TextureLayered.xml b/doc/classes/TextureLayered.xml
index 13679908d7..3445329f32 100644
--- a/doc/classes/TextureLayered.xml
+++ b/doc/classes/TextureLayered.xml
@@ -9,6 +9,42 @@
 	<tutorials>
 	</tutorials>
 	<methods>
+		<method name="_get_format" qualifiers="virtual const">
+			<return type="int" enum="Image.Format" />
+			<description>
+			</description>
+		</method>
+		<method name="_get_height" qualifiers="virtual const">
+			<return type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_get_layer_data" qualifiers="virtual const">
+			<return type="Image" />
+			<argument index="0" name="layer_index" type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_get_layered_type" qualifiers="virtual const">
+			<return type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_get_layers" qualifiers="virtual const">
+			<return type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_get_width" qualifiers="virtual const">
+			<return type="int" />
+			<description>
+			</description>
+		</method>
+		<method name="_has_mipmaps" qualifiers="virtual const">
+			<return type="bool" />
+			<description>
+			</description>
+		</method>
 		<method name="get_format" qualifiers="const">
 			<return type="int" enum="Image.Format" />
 			<description>
diff --git a/doc/classes/VisualInstance3D.xml b/doc/classes/VisualInstance3D.xml
index 1aae85c7e1..7efa1f4df8 100644
--- a/doc/classes/VisualInstance3D.xml
+++ b/doc/classes/VisualInstance3D.xml
@@ -9,6 +9,11 @@
 	<tutorials>
 	</tutorials>
 	<methods>
+		<method name="_get_aabb" qualifiers="virtual const">
+			<return type="AABB" />
+			<description>
+			</description>
+		</method>
 		<method name="get_aabb" qualifiers="const">
 			<return type="AABB" />
 			<description>