The .gitignore now ignores all dotfiles at the repo root, other than those
explicitly not ignored with !.

Flake8 will spend a long time scanning the virtualenv files dir if the
readme instructions are followed, creating one at /.venv.

It's a bit distracting when running tests during development to have
coverage printed every time, and slows down the tests somewhat. Coverage
and mypy are now run by CI, but not by default with pytest.

It was un-covered in the coverage report.

I need to know that these code paths are hit by tests.

These errors are not triggered by current tests.

This can only occur because of programmer error.

These errors are caused by bad usage docs, they shouldn't ever trigger
DocoptExit as they're not the end user's fault.

A lot of docopt tests call docopt() without specifying argv, which uses
`sys.argv` by default, so a predictable value for it is necessary.

I'm planning to make the error messages more user-friendly, (especially
"Warning: found unmatched (duplicate?) arguments ..."), so I need to verify
what the messages currently are so I can ensure that any changes are expected.