convert Polygon2D to normal AMD spec
adds Polygon2D#isConvex(), adds unit tests

updates Polygon2D#isClockwise()
updates Polygon2D#intersectsPolygon(poly)
adds new Polygon2D methods

adds Polygon2D#offsetShape( distance )
adds Polygon2D#reduceVertices( minEdgeLen )
adds Polygon2D#scaleSize( vec )
Ellipse and Rect lazy-require Polygon2D
adds Polygon2D#toMesh
lazy-load Line3D in Ray3D#toLine3DWithPointAtDistance
Merge branch 'feature-polygon2d' into develop