Blender Git Loki

Fix T43735 painting on perpendicular to the screen polygons is
problematic (still!)

It seems due to floating point precision issues we have to account for
even more cases.

Added colinear check for one more triangle edge-vertex and assumed that
if no collision test is found then triangle is completely inside box.

Such cases are mostly from float precision not catching triangle just
outside bucket. Now tests are much better for simple tests (paint/flood
fill cube from ortho view, paint sphere), however there are still some
rare cases of stray pixels.