Blender Git Loki

Subsurf: Remove edit mesh modifier callbacks

Those were used for partial updates during edit mode, which will
not be possible anymore with OpenSubdiv.

Optimization for OpenSubdiv would be to re-use topology refiner
if topology does not change. But this is something to be done
for both edit and object modes, no need to have separate code
paths for those.

This commit makes OpenSubdiv to properly work in edit mode.