![Unfolded sphere](https://farm8.staticflickr.com/7464/15880804609_88b0865685_z.jpg)

`unfold` reads a binary STL file on standard input and generates a
SVG that contains the triangles "folded flat" so that they can be
laser cut.  It will output multiple groups in the SVG file that
will need to be re-arranged to fit on the laser cutter bed.

More info: https://trmm.net/Unfolding_STL

This is a work in progress -- it is not yet feature complete.
Among the features that it could use:

* A better heuristic for finding the maximum non-overlaping set of triangles
(Currently breadth-first search is used, with a slight preference for coplanar
triangles)

* Tabs for securing parts together.

* Collapsing of very small or very thin triangles.

* Marking mountain or valley folds.