Blender Git Loki

Fix T37812, anchored sculpting on a flat plane created artifacts.

This must be an ancient bug, almost as old as anchored brushes
themselves. Code did not do sphere node intersection against original
bounding boxes if an anchored brush required it. In practice this was
not easy to see because vertices were displaced inside brush radius most
of the time. However in the provided report file, displacement was far
away from the brush sphere, making the issue apparent.

Also added original check in proxy combination code (might cause issues
with dyntopo but quick test did not show any) and did some style int ->
bool style changes.