Changed the current function GetDirectionsOfSteepestSlope to GetDirectionsOfSteepestSlope_BorderCheckingVersion; the new GetDirectionsOfSteepestSlope now uses direct linear algebra on the 3 points instead of checking every point in the border
Ignore degenerate rows in GetDirectionsOfSteepestSlope, making drawing pure-planar triangles work correctly; this also takes care of the issue with collinear points