Rect points

Allows getting "the effective points" of graphic rectangles, round rectangles, and regular polygons.
This allows for some things that are difficult at present: setting the points of a freeform polygon to one of several regular polygon objects; moving an image around the points of a regular polygon, etc.
I think you're probably correct. The whole points/oldpoints/realpoints/markerpoints and delpoints()  thing is quite confusing and undocumented. I found that realpoints did what I wanted and stopped there. I'll see about patching the leak.