Refactor 2 Debug

This work focuses on improving the accuracy of the operations that are being performed.

### Goals

  * [x] Don't produce NaNs in output
  * [ ] ~~Don't produce nonsense polygons in BSP construction~~
  * [ ] ~~Don't clip with things that aren't there~~

### Bonus goals

  * [ ] ~~Improve accuracy by doing things closer to `(0,0,0)` for float reasons.~~
  * [ ] ~~I dunno.~~

## NEW UNIFIED GOAL

  * [ ] Make a base for further operations instead of a master stab-in-the-dark issue

I'm going to clean up the code and merge it without too much extra actual flow changes, then make individual attempts to fix problems rather than stretching it out into a single effort.