The Cython Re-release.

Moving regions from sixel branch into main as it's much faster.

Rewrite of regioning algorithm in cython for roughly 60x speedup. This is a first step towards a larger goal of cythonizing all rendering to be performant enough to handle sixel graphics. Follow the sixel branch to keep track of this progress.

Several minor bug fixes in this update as well.

This will likely be last release of this year as Advent of Code descends upon me and consumes the remainder of my free time.