remove CmdOptions since we can use argparse.Namespace()

[RonnyPfannschmidt]

Thanks for submitting a PR, your contribution is really appreciated!

Here's a quick checklist that should be present in PRs (you can delete this text from the final description, this is
just a guideline):

• Create a new changelog file in the changelog folder, with a name like <ISSUE NUMBER>.<TYPE>.rst. See changelog/README.rst for details.
• Target the master branch for bug fixes, documentation updates and trivial changes.
• Target the features branch for new features and removals/deprecations.
• Include documentation when adding new features.
• Include new tests or update existing tests when applicable.

Unless your change is trivial or a small documentation fix (e.g., a typo or reword of a small section) please:

• Add yourself to AUTHORS in alphabetical order;

[coveralls]

Coverage increased (+0.05%) to 92.961% when pulling 87f2003 on RonnyPfannschmidt:cmdoptions-removal into f8791c9 on pytest-dev:features.

[nicoddemus]

Great, thanks!