Whoops. Forgot I didn't need path_is_descendant anymore.
Run sphinx-quickstart to generate the documentation boilerplate
Convert README.md into reStructuredText
Translate in-code API documentation to Sphinx-dialect reStructuredText

(And move certain TODOs into issues #21, #22, and #23)
Set up sphinx.ext.autodoc

(It's ugly and primitive compared to ePyDoc, but it's Py3-compatible,
 it allows me to use ReadTheDocs, and it's acceptable for such a small
 script until I can write a better alternative.)