Blender Git Loki

AnimSys2: Joining Meshes with Shapekeys

It is now possible to join several meshes that have shapekeys (using Ctrl-J). This is still a 'first draft' version, as there are still a few cases things that need ironing out still (*see notes).
Be aware that this may very well crash or screw things up in weird and wonderful ways.

Where possible, I've attempted to add some comments and general cleanups to this code to make it easier to follow.

Notes (i.e. things that will be fixed in upcoming commits):
- Joining of shapekeys will only happen if the destination mesh has some shapekeys. If one of the meshes being merged into it has shapekeys but it doesn't, these are ignored/lost.
- IPO's are currently not transferred across yet...