Blender Git Loki

Brush Stroke: Use world spacing option

Quick hack to compute the stroke step using the world space location of
the brush over the mesh instead of the screen space distance, so the
user can avoid a lot of artifacts when sculpting across curved surfaces.
This would need to be implemented for texture/vertex/weight paint in the
future to keep the stroke system consistent.
It still has some problems with brushes that use original coordinates.