Improve code coverage

[zyteka]

The current testing code coverage is only about 50%. While pyreal does not currently have a required coverage threshold, there are likely important blocks of code being missed right now.

This issue will be addressed by:

1. Increasing the code coverage to an appropriate level (ie, covers all important functionality). Probably ~80%.
2. Establishing and documenting formal guidelines for testing code coverage when making PRs, as well as establishing formal guidelines for code coverage for pyreal.