Geometry mapping

crease pattern <-> triangulation <-> faces

What we came up with to-date:

• We should play with faces, not geometries, as they allow us to access the verrtexes by-hand.
• There is only Face3 in three.js. To represent FaceN we need to triangulate.
• To handle one face on a crease pattern (FaceN), we should have our own object storing the faces (we don't need / should not play with nested geometries)

Handling edges assignment

• we need some edge object, that will know its state
• when modifying edge assignment it should "fold"
• there has to be a knowledge in the system about what faces the edge is adjacent to - it's a reverse of responsibility, but the edge could have faces its adjacent to saved, and then when its assignment changes, it can notify the geometry about it.

SOLVER

• Using Verlet integration to improve numerical stability: https://en.wikipedia.org/wiki/Verlet_integration