ObjectTraits redesign.
ObjectTraits redesign continued.
Extend TransformationProxyTrait.

- add 'transformSnap' and 'transformSnapPos' roles.
PersistentNodeTrait: add removeInvalidTraitNames(...); bugfixes
Fixes.
NodeEditor: Add [ctrl] + [i] to instantiate nodes.
NodeEditor/Tools/MeshMenu: Add "Embed meshes" and "Scale texture coords"
ObjectTraits: Add ImportSubtreeTrait.
ObjectTraits: Add ExternalScriptTrait.