Blender Git Loki

Sculpting on shapekeys
======================

All this work with sculpting on armatured/deformed mesh allowed to
implement sculpting on non-locked keys very easy -- just use the same
approach of propagating offsets from deformed PBVH to "sculpting layer".

- If key is locked, then old logic would be used.
- If there's multires modifier enabled, sculpting would happen on multires.