Wumpus

Copperbox revision 709.

Labels are now Pictures rather than an adhoc datatype. They are drawing inside a clipping rectangle which must be supplied by the user. This is inconvenient - a user must guess the text size and check the output to make sure the text has not been clipped. But it does mean that we can have an static bounding box and can then use the picture combinators to arrange labels. The only other way to get the bounding box would be some fancy bidirectional interface to GhostScript (PostScript has the reflective capability to get the bounding box of text output), but would add dependencies and make things far too complicated.