wumpus-core

Copperbox revision 1613.

I've renamed the Single constructor to Leaf in the Picture datatype.

With hindsight, the Picture datatype is rather inadequate - it is biased towards many pictures (graphic within an affine frame) of single primitives (path, text) rather than few pictures of many primitives. In the PostScript output, the extra use of affine frames is optimized away as most of the frames are the identity frame; but for SVG, the output generates many 'g' blocks which is an extra layer of nesting.

Picture would be better as a binary tree, where Leaf is a list of Primitives and Picture is a binary node. I'm going to look at moving to this in the next round of work.