make is_quad_convex_v3() more strict, check if normal is OK before using as a rotation axis.
make is_quad_convex_v2,3() check for ISECT_LINE_LINE_CROSS intersection (that the lines actually cross each other).


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54511 954f8c5b-7b00-dc11-b283-0030488c597c