Update CLI and add tests #83
Description
The CLI is out of date. There are some additional functions that should be added and some changes that would cause some functions not to work right now.
Ideally this can be done in concert with adding "Unknown" types by default using the new pandas StringArray. Then it would be a bit easier to save and load data.
Tests are also needed. See here: https://click.palletsprojects.com/en/7.x/testing/