Blender Git Loki

Mask feather self-intersection check

Enable self-intersection check for preview. In own tests average
time for this operation on mango files was ~0.0015sec, and it was
like 20 splines max which still gives pretty smooth performance
on my core quad machine.

Would think let's check how it works for now, if it'll give some
issues here, would just avoid tessellation on every redraw by
storing tessellation in some cache (probably in mask user).

Another change is related on a way which loop to collapse.
Changed length check with AABB size check. A bit slower but
should be a bit more predictable.