Multi-threading support for transform modes: bevel-weight, crease,
push-pull, rotate, shear, shrink-fatten, skin-resize, to-sphere,
trackball & translate.
This is done using a parallel loop over transform data.
From testing a 1.5million polygon mesh on a 32 core system
the overall performance gains were between ~20-28%
To ensure the code is thread-safe arguments to shared data are const.
Reviewed By: mano-wii
2d4ec90497