[Feature] Polyhedral nets

[tesseralis]

Support the display of polyhedral nets.

Initially, we'd just want a toggle somewhere in the Viewer that lets the user switch between the net and the polyhedron.

Considerations:

• operations should be disabled when on the net view
• probably want to display it as an svg
• the net calculation algorithm should determine a "pretty" net. i.e. one that fits the viewport, and one that keeps interesting facets of the polyhedron intact, like cupola faces.

If we're super cool, we could do a folding/unfolding animation: https://www.youtube.com/watch?v=Igf4BXkERyI

But this is actually really really hard, so it's not a priority.

[funvill]

I came looking for this feature after viewing one of your talks on Youtube.

Great work on this project. I am using it to help make LED polyhedral https://www.instagram.com/p/DBzao2LT6Gn/?img_index=1