Blender Git Loki

Much cleaner and satisfying code in weightvg modifiers' "init": copy only the CD_DEFORMVERT data layer (if it's the org one), and not the whole DerivedMesh!

Quite oddly, for Proximity mod, this increases the performances of the apply func (about 20-25%, e.g. from 0.04 to 0.03 sec), but decreases the global framerate (e.g. in TEST_5 scene of testing file, I lose about 7%, from 4.6 to 4.3fps (open ATI driver)...).