Hyperbolic tilings library

New: I added an Instructable about how to use this to make cookies:
[https://www.instructables.com/id/Hyperbolic-Cookies/](https://www.instructables.com/id/Hyperbolic-Cookies/).

This is an OpenSCAD library for creating customizable tilings of the hyperbolic plane (in the Poincaré disk model) by triangle groups.

* A triangle group is defined by a triplet (p,q,r) where 1/p+1/q+1/r < 1, and invoked as `triangle_group(p,q,r)`. The number 0 represents the special value ∞. Any infinite numbers must precede finite numbers (i.e. `triangle_group(0,2,3)` is legal, while `triangle_group(2,0,3)` is not — this would be the same group anyway).

* Tessellation data is computed from the triangle group with `tgroup_tessellation_data(group, depth)`, where the `depth` parameter is the number of consecutive reflections from the center tile.

* The modules building the 3d object use this tessellation data; a few modules are provided as examples, such as `tessellation_simple` and `tessellation