Wumpus

Copperbox revision 889.

Some tidying up after the changes to the picture types.

Unfortunately I didn't fully work through the changes to the pictures types, and I've realized that in the current form I'll be sending a lot of redundant graphics state changes to PostScript. Essentially I've put all attribute data in the leaves of the tree (the picture type is a tree; paths, labels are the leaves); this is fine for SVG but not good for PostScript. With PostScript I use gsave ... grestore like local in Haskell's reader (environment) monad, but as I've distributed everything to the leaves effectively I'll only ever be running one command inside local.