Improve polygon/vector triangulation

[soywiz]

• https://www.emanueleferonato.com/2011/09/12/create-non-convex-complex-shapes-with-box2d/
• https://alienryderflex.com/polygon_triangulation_with_hole.shtml
• https://alienryderflex.com/triangulation/
• https://cs.stackexchange.com/questions/23137/divide-self-intersecting-polygon
• https://cs.stackexchange.com/questions/29376/divide-self-intersecting-polygon-into-simple-polygons
• https://en.wikipedia.org/wiki/Doubly_connected_edge_list
• https://stackoverflow.com/questions/753140/how-do-i-determine-if-two-convex-polygons-intersect#:~:text=To%20be%20able%20to%20decide,polygons%20forms%20such%20a%20line.
• https://gamma.cs.unc.edu/SEIDEL/