also merge all bones isn't needed. we should do that by default
This also now uses dictionary matching to find bone types like hips, spine, and chest that should be merged.
Deletes bone shared and merges armatures, and parents bones back, causing a seamless merge.
- made remove doubles a blender modal. this way the code can run over multiple frames.
- Since remove doubles is async now, the user gets feedback on which shapekey and mesh is being worked on
- this does not remove doubles correctly yet, but is very close to ready
989onan