New method based on expanding the corners of a polygon. Still slow.
Another new method, like corners but only allows points on edges

this seems to be reasonably fast, but still not great. If I limit it to
5-sided polygons, it gets through the 15x15 2 or 3 times faster than
gurobi, but that's not spectacular
draw every segment as it's generated
allow more edges, but prune every step
faster algorithms, limited number of sides, and pruning every step