Improve Sphinx documentation extraction

[ChrisEPhifer]

As of right now, we're naively extracting documentation from Python docstrings. This could be improved significantly by putting in some more manual work: Careful consideration of what double-underscore methods to include, what order to present the documentation, etc.

Personally, I like the guiding principle of "tell a story" - Even documentation of a module's interface should have a natural flow that makes its intended use clear.