fixed PointUtilities::clockwise

different internal sort on jRuby revealed problem
should not sort by cross_product, is is not a transitive function (when spanning >180 degrees)
now sorting clockwise in quadrants by slope (will need to move to non-FP solution for speed)
should now sort all convex (including with collinear sections) and star-shaped polygons
clockwise? and anty-clockwise? were similarly only passing fully convex points
now passing for all convex (including with collinear sections) and star-shaped polygons
...but some Polygon & Mesh tests are failing - inside & outside tests depended upon flawed convexity of clockwise?...