Wumpus

Copperbox revision 727.

I've changed to BoundingBox module as I want the bounding box of pictures to be more accessible, then I can get add functionality like TikZ's nodes.

However, because Pictures are a functional type Frame -> (WumpusM (), BoundingBox) I can't access the bounding box how I would like. I'm wondering if Picture should be a monad transformer of Writer and Reader (Reader supplies the enivronment - here a frame, and Writer supplies the output so far a string of PostScript text and the bounding box).

If I did change to a monad I could use all the tricks (applicative combinators, do notation) to get rid of some of the messy Picture $ \frm -> let ... - code in Basic.hs that has taken hold.