Wumpus

Copperbox revision 874.

I've made ellipse a drawing primitive alongside path and label. This is for efficiency reasons. Circles can be simulated with Bezier curves but it takes 8 sections to get a reasonable approximation.

Adding arc to the primitive path type (with curve and line segment) would follow how PostScript works but it would make affine transformations on paths very difficult. Similarly finding the bounding box of a path would also be difficult.