Fix warning about functions defined but not used [-Wunused-function]

Fixes the following GCC 5 warnings:
```
core/io/zip_io.h:128:26: warning: 'zlib_filefunc_def zipio_create_io_from_file(FileAccess**)' defined but not used [-Wunused-function]
core/script_debugger_remote.cpp:110:17: warning: 'ObjectID safe_get_instance_id(const Variant&)' defined but not used [-Wunused-function]
drivers/unix/socket_helpers.h:103:12: warning: 'int _socket_create(IP::Type&, int, int)' defined but not used [-Wunused-function]
drivers/unix/socket_helpers.h:45:15: warning: 'size_t _set_sockaddr(sockaddr_storage*, const IP_Address&, int, IP::Type)' defined but not used [-Wunused-function]
drivers/unix/socket_helpers.h:76:15: warning: 'size_t _set_listen_sockaddr(sockaddr_storage*, int, IP::Type, IP_Address)' defined but not used [-Wunused-function]
editor/editor_fonts.cpp:40:24: warning: 'Ref<BitmapFont> make_font(int, int, int, int, const int*, const Ref<Texture>&)' defined but not used [-Wunused-function]
editor/editor_themes.cpp:85:26: warning: 'Ref<StyleBoxFlat> change_border_color(Ref<StyleBoxFlat>, Color)' defined but not used [-Wunused-function]
editor/import/editor_import_collada.cpp:493:13: warning: 'void _generate_normals(const PoolVector<int>&, const PoolVector<Vector3>&, PoolVector<Vector3>&)' defined but not used [-Wunused-function]
editor/import/editor_import_collada.cpp:524:13: warning: 'void _generate_tangents_and_binormals(const PoolVector<int>&, const PoolVector<Vector3>&, const PoolVector<Vector3>&, const PoolVector<Vector3>&, PoolVector<float>&)' defined but not used [-Wunused-function]
editor/pvrtc_compress.cpp:118:13: warning: 'void _compress_etc(Image*)' defined but not used [-Wunused-function]
modules/etc/image_etc.cpp:89:13: warning: 'void _decompress_etc1(Image*)' defined but not used [-Wunused-function]
modules/etc/image_etc.cpp:93:13: warning: 'void _decompress_etc2(Image*)' defined but not used [-Wunused-function]
modules/gdscript/editor/gdscript_highlighter.cpp:46:13: warning: 'bool _is_whitespace(CharType)' defined but not used [-Wunused-function]
scene/2d/cpu_particles_2d.cpp:510:14: warning: 'float rand_from_seed_m1_p1(uint32_t&)' defined but not used [-Wunused-function]
scene/3d/cpu_particles.cpp:474:14: warning: 'float rand_from_seed_m1_p1(uint32_t&)' defined but not used [-Wunused-function]
scene/resources/default_theme/default_theme.cpp:123:20: warning: 'Ref<Shader> make_shader(const char*, const char*, const char*)' defined but not used [-Wunused-function]
scene/resources/default_theme/default_theme.cpp:130:24: warning: 'Ref<BitmapFont> make_font(int, int, int, int, const int*, const Ref<Texture>&)' defined but not used [-Wunused-function]
```

Had to split `core/io/zip_io.h` into header and .cpp file without 'static' keyword.

Not fixed yet (static definition in header used in some files but not all):
```
modules/websocket/lws_helper.h:111:13: warning: 'void _lws_make_protocols(void*, int (*)(lws*, lws_callback_reasons, void*, void*, size_t), PoolVector<String>, _LWSRef**)' defined but not used [-Wunused-function]
```

Also fixed a couple other warnings missed in previous commits.

1 files changed, 0 insertions, 114 deletions

diff --git a/editor/import/editor_import_collada.cpp b/editor/import/editor_import_collada.cpp
index 31c1886d32..60ca66e464 100644
--- a/editor/import/editor_import_collada.cpp
+++ b/editor/import/editor_import_collada.cpp
@@ -490,120 +490,6 @@ Error ColladaImport::_create_material(const String &p_target) {
 	return OK;
 }
 
-static void _generate_normals(const PoolVector<int> &p_indices, const PoolVector<Vector3> &p_vertices, PoolVector<Vector3> &r_normals) {
-
-	r_normals.resize(p_vertices.size());
-	PoolVector<Vector3>::Write narrayw = r_normals.write();
-
-	int iacount = p_indices.size() / 3;
-	PoolVector<int>::Read index_arrayr = p_indices.read();
-	PoolVector<Vector3>::Read vertex_arrayr = p_vertices.read();
-
-	for (int idx = 0; idx < iacount; idx++) {
-
-		Vector3 v[3] = {
-			vertex_arrayr[index_arrayr[idx * 3 + 0]],
-			vertex_arrayr[index_arrayr[idx * 3 + 1]],
-			vertex_arrayr[index_arrayr[idx * 3 + 2]]
-		};
-
-		Vector3 normal = Plane(v[0], v[1], v[2]).normal;
-
-		narrayw[index_arrayr[idx * 3 + 0]] += normal;
-		narrayw[index_arrayr[idx * 3 + 1]] += normal;
-		narrayw[index_arrayr[idx * 3 + 2]] += normal;
-	}
-
-	int vlen = p_vertices.size();
-
-	for (int idx = 0; idx < vlen; idx++) {
-		narrayw[idx].normalize();
-	}
-}
-
-static void _generate_tangents_and_binormals(const PoolVector<int> &p_indices, const PoolVector<Vector3> &p_vertices, const PoolVector<Vector3> &p_uvs, const PoolVector<Vector3> &p_normals, PoolVector<real_t> &r_tangents) {
-
-	int vlen = p_vertices.size();
-
-	Vector<Vector3> tangents;
-	tangents.resize(vlen);
-	Vector<Vector3> binormals;
-	binormals.resize(vlen);
-
-	int iacount = p_indices.size() / 3;
-
-	PoolVector<int>::Read index_arrayr = p_indices.read();
-	PoolVector<Vector3>::Read vertex_arrayr = p_vertices.read();
-	PoolVector<Vector3>::Read narrayr = p_normals.read();
-	PoolVector<Vector3>::Read uvarrayr = p_uvs.read();
-
-	for (int idx = 0; idx < iacount; idx++) {
-
-		Vector3 v1 = vertex_arrayr[index_arrayr[idx * 3 + 0]];
-		Vector3 v2 = vertex_arrayr[index_arrayr[idx * 3 + 1]];
-		Vector3 v3 = vertex_arrayr[index_arrayr[idx * 3 + 2]];
-
-		Vector3 w1 = uvarrayr[index_arrayr[idx * 3 + 0]];
-		Vector3 w2 = uvarrayr[index_arrayr[idx * 3 + 1]];
-		Vector3 w3 = uvarrayr[index_arrayr[idx * 3 + 2]];
-
-		real_t x1 = v2.x - v1.x;
-		real_t x2 = v3.x - v1.x;
-		real_t y1 = v2.y - v1.y;
-		real_t y2 = v3.y - v1.y;
-		real_t z1 = v2.z - v1.z;
-		real_t z2 = v3.z - v1.z;
-
-		real_t s1 = w2.x - w1.x;
-		real_t s2 = w3.x - w1.x;
-		real_t t1 = w2.y - w1.y;
-		real_t t2 = w3.y - w1.y;
-
-		real_t r = (s1 * t2 - s2 * t1);
-
-		Vector3 tangent;
-		Vector3 binormal;
-
-		if (r == 0) {
-
-			binormal = Vector3();
-			tangent = Vector3();
-		} else {
-			tangent = Vector3((t2 * x1 - t1 * x2) * r, (t2 * y1 - t1 * y2) * r,
-					(t2 * z1 - t1 * z2) * r)
-							  .normalized();
-			binormal = Vector3((s1 * x2 - s2 * x1) * r, (s1 * y2 - s2 * y1) * r,
-					(s1 * z2 - s2 * z1) * r)
-							   .normalized();
-		}
-
-		tangents.write[index_arrayr[idx * 3 + 0]] += tangent;
-		binormals.write[index_arrayr[idx * 3 + 0]] += binormal;
-		tangents.write[index_arrayr[idx * 3 + 1]] += tangent;
-		binormals.write[index_arrayr[idx * 3 + 1]] += binormal;
-		tangents.write[index_arrayr[idx * 3 + 2]] += tangent;
-		binormals.write[index_arrayr[idx * 3 + 2]] += binormal;
-	}
-
-	r_tangents.resize(vlen * 4);
-	PoolVector<real_t>::Write tarrayw = r_tangents.write();
-
-	for (int idx = 0; idx < vlen; idx++) {
-		Vector3 tangent = tangents[idx];
-		Vector3 bingen = narrayr[idx].cross(tangent);
-		float dir;
-		if (bingen.dot(binormals[idx]) < 0)
-			dir = -1.0;
-		else
-			dir = +1.0;
-
-		tarrayw[idx * 4 + 0] = tangent.x;
-		tarrayw[idx * 4 + 1] = tangent.y;
-		tarrayw[idx * 4 + 2] = tangent.z;
-		tarrayw[idx * 4 + 3] = dir;
-	}
-}
-
 Error ColladaImport::_create_mesh_surfaces(bool p_optimize, Ref<ArrayMesh> &p_mesh, const Map<String, Collada::NodeGeometry::Material> &p_material_map, const Collada::MeshData &meshdata, const Transform &p_local_xform, const Vector<int> &bone_remap, const Collada::SkinControllerData *p_skin_controller, const Collada::MorphControllerData *p_morph_data, Vector<Ref<ArrayMesh> > p_morph_meshes, bool p_use_compression, bool p_use_mesh_material) {
 
 	bool local_xform_mirror = p_local_xform.basis.determinant() < 0;