Mechanical Planetarium - Tuned

This is an optimized version of the "Mechanical Planetarium" model by Zippitybamba.

I printed a few parts of the original model on my Prusa I3 MK3S, and I wasn't satisfied with how they fit. This sent me down a rabbit hole of refactoring and tuning the file until I could print it with insanely low tolerances of about 0.12mm on average.

The original model is truly excellent and deserves to be on the main page for a long time. I put in a lot of time tuning this, so I thought I should share what I've done.

A quick summary of edits:
- Combined the base and upper mechanism into one file.
- Added toggles for rendering each object.
- Refactored source for ease of reading and editing.
- Switched to the English fork of "Getriebe.scad" named "Gears.scad". Translated by Chris Spencer. https://github.com/chrisspen/gears
- Added several customizer sliders to:
- Compensate for printer Z thickness.
- Control spacing for meshing of the gears in the base.
- SCALING! The model i