Generate documentation, standardize on one docstring format

[madig]

I propose we not only write, but also generate documentation to make user's lives easier.

See https://github.com/RookieGameDevs/revived/tree/master/revived and https://revived.readthedocs.io/en/stable/api.html for an example. Note the structure of the docstrings and what they're turned into.

So, we need to:

1. Standardize on a format to write docstrings in that tools like Sphinx can automatically generate something from...
2. ...and well, basically, use Sphinx.
3. Host at ReadTheDocs?

[madig]

https://sphinxcontrib-napoleon.readthedocs.io/en/latest/example_google.html