- `curve_horn_*`: actually *combine* geometry properly.

- https://docs.rs/nalgebra/0.19.0/nalgebra/geometry/struct.Translation.html#method.prepend_translation -
  see this for how to create Matrix4 from a translation
- Try a translation on an OpenMesh, and then try connect_single!

- Look at everything in README.md in automata_scratch.
- Implement some of the tougher examples from the above too, e.g. the
  triple nested spiral
- Lots of Rust-kosher refactoring (once I understand Rust better)
- Grep for all TODOs in code, really
- Actual Rust-style docs!

- Fix links in tri_mesh docs that use relative paths & do a PR?