Wumpus

Copperbox revision 628.

Added a prototype implementation of de Casteljau's curve subdivision algorithm.

It's implemented with just affine space operations and points and vectors. While this isn't news to someone well versed in geometry it was revealing to me that I didn't need extra objects (line segments) or new operations. I had a lot of trouble studying presentations of de Casteljau's algorithm as I thought the presentations were doing point addition which is of course a geometric no-no, it turns out they weren't of course.