Surface deform weight calculation assigned weights in a non-uniform
way that caused vertices to deform upon binding.
This was caused by the face-corner angle being used in
calculations which where squared & scaled.
Causing a triangle fan of many thin faces to have a much greater
influence compared to the same shape made from a single triangle.
Change the calculation of the weight so each face-corner is scaled
by it's angle.
fc9f1b1754