Node3D gizmo improvements

* Clean-up of node_3d_editor_plugin.{h,cpp}: removed unused code, fixed some bugs.
* Moved node_3d_editor_gizmos.{h,cpp} to editor/plugins.
* Added support for multiple gizmos per node. This means custom gizmos will no longer override the built-in ones and that multiple gizmos can be used in more complex nodes.
* Added support for handle IDs. When adding handles to a gizmo, an ID can be specified for each one, making it easier to work with gizmos that have a variable number of handles.
* Added support for subgizmos, selectable elements that can be transformed without needing a node of their own. By overriding _subgizmo_intersect_frustum() and/or _subgizmo_intersect_ray() gizmos can define which subgizmos should be selected on a region or click selection. Subgizmo transformations are applied using get/set/commit virtual methods, similar to how handles work.

1 files changed, 1 insertions, 0 deletions

diff --git a/scene/scene_string_names.h b/scene/scene_string_names.h
index a141c2b3aa..eddb0c33eb 100644
--- a/scene/scene_string_names.h
+++ b/scene/scene_string_names.h
@@ -156,6 +156,7 @@ public:
 
 	StringName _spatial_editor_group;
 	StringName _request_gizmo;
+	StringName _clear_subgizmo_selection;
 
 	StringName offset;
 	StringName unit_offset;