Generalise papercraft instructions as a library, for any mesh with cuts

[timhutton]

The code is almost all there to make a useful library that would convert a mesh into SVG and instructions, ready for printing.

Features:

• Would take as input a mesh, made of contiguous single-color face sets, or a mesh with cuts.
• Would flatten the pieces, add tabs and labels and ridge/valley folds.
• Would composite onto pages for printing.
• Instructions for how to join would be automatically produced.

Questions:

• What existing solutions exist?
• Can we find a joining sequence that minimises fiddlyness?
• Can we minimise the problem of joining the last piece?
• Integrate with laser-cutting solutions?