Snowflake growth simulation in OpenSCAD

This is a randomized OpenSCAD implementation of the [Reiter cellular automaton algorithm](https://pdfs.semanticscholar.org/26f9/a97b0da14d8d555a17b610ba3b7726457535.pdf) for simulating snowflake formation.

You can customize a lot of parameters. If you just want to re-run and get a new snowflake, change the random seed.

There are three ways of extending the flake into the third dimension. You can have variable thickness based on the ice density in the simulation; you can have constant thick