wumpus

Copperbox revision 2549.

I've bumped version numbers in the cabal files in Wumpus-Basic and Wumpus-Drawing, and I've changed the representation of AbsPath in Drawing. I think Wumpus-Drawing should be able to manage with one path type, rather than need both absolute paths and relative paths. The first step towards this is changing AbsPath so it supports cheap movement, with cheap movement it should be able to cover the use-cases that RelPath previously handled.