Blender Git Loki

* fixed crash when a mesh with no UVs was painted.
* fixed more bugs in face clipping, clip_line wasnt working when the line was horiz/vertical. unning exactly on the clipping rectangle bounds.
* testing if a point was inside a triangle didnt work if the point was touching the triangles edge, added IsectPT2Df_limit(...) for this rather then using 3 point/line intersection checks.
...Cant find anymore bugs in face clipping now :)