Bring the codebase documentation up to modern standards.
Review Request #10986 — Created April 2, 2020 and submitted
This fixes up the docstrings in some of the older code to meet the
modern Beanbag documentation standards. This mostly just means adding
missing arguments, return values, etc. to functions, docstrings for
modules, and fixing up some presentational issues.
Just went through and manually verified the new changes. We don't
actually have formal doc building yet.