Wumpus

Copperbox revision 646.

Initial work to add text labels.

Labels are going to be problematic as I can't see how to establish their size or bounding box. PostScript has the stringwidth command but I don't want to have PostScript variables within Wumpus, that's do say I don't want a reflection mechanism between Wumpus and PostScript. I think I will augment labels with a clipping path to draw the text inside at some point. Then Wumpus can access the geometry of the clipping path, though drawings will need visually checking after they have been created to ensure all the label text is within clipping path.