* New plugin system to control the whole import workflow
* Can add options and run code at every import step (general, per node, mesh, animation, material etc.)
This constitutes a first version of these plugins. The ability to interact with the import preview dialog will likely be added later on.
Convert GLTF Document to use ImporterMeshInstance3D.
Add a GLTFDocument extension list and an extension for converting the importer mesh instance 3d to mesh instance 3d.
Use GLTF module when the editor tools are disabled.
Modified the render server to be less restrictive on matching blend arrays and have more logging.
Misc bugs with multimesh.
Always index the meshes.
For the time being we don't support writing a description for those, preferring
having all details in the method's description.
Using self-closing tags saves half the lines, and prevents contributors from
thinking that they should write the argument or return documentation there.
Fix issue when two skeletons end up directly parented.
Prevent animating TRS for skinned Mesh node.
Fix animating weights on meshes with targets but no weights.
