~brenns10/subc

Hide aliases from help output, or completion
Release v0.4.1 with py.typed
Add docstring updates and README.rst update
Ignore subc.egg-info
Replace comment-annotations with real ones (py36+)

This commit also swaps out some "pass" for docstrings, which brings test
coverage to 100% on the pytest-cov report. It's a bit weird that it has
to be that way, but whatever.
Add shortest_prefix option, and tests
Allow a default subcommand to be set, v0.3.0
Allow command subclasses, which are not instantiated