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An improved CrazySpace correction is now used for Armature modifiers that use
vertex groups, and that are the first enabled modifiers in the stack. This is
a a specific case, but also a common one.
http://www.blender.org/development/current-projects/changes-since-244/skinning/
Implementation Notes:
- The quaternion crazyspace correction is still used for modifiers other than
the armature modifier.
- Modifiers can now provide a deform matrix per vertex to be used for
crazyspace correction, only the armature modifier implements this now.