Blender Git Loki

BMesh: Fix for previous own fix (re-enable DynamicPaint previews in Object mode).

In fact, we have to add a CD_WEIGHT_MCOL layer (if not yet present) when updating CD_WEIGHT_MLOOPCOL, else with modifiers modifying the topology (like subsurf), it will sigsev.

That step should probably be done at tesselation time, though�?�