Oval points

Hot on the heels of allowing effective points for rects, roundrects, and regular polygons, I figured out how to allow points for ovals by treating them as roundrects with a radius equal to the greater of the the rect width or height. Since the previous pull request hasn't been merged into master yet, it looks like I'm actually adding more lines than are in this pull request - there are actually very few, since the heavy lifting was already done for roundrects. I created this branch off the rect_points branch, since it leverages that work.