Wumpus

Copperbox revisions 685 & 686.

Initial attempt at creating paths (i.e. concatenations of curves and line segments) by function composition.

The current code is fairly ugly, but I can't think of any other code bases to crib from so I'm stuck for inspiration. As far as I can tell, Clastic and other functional graphics programs that are 'functions from Point to ...' generally have the same type as the image of the function. At the moment Wumpus has functions from Point to various types of object (polygon, curve, line segment etc.), which are drawn to PostScript some time later. For paths Wumpus uses a sum of LineSegment and Curve - it generates yet more syntax rather than an image.