Bug Fixes and Added ReadTheDocs Documentation

Fixed various minor bugs, updated documentation, added more options to example script.

pySEAS early release

Welcome to pySEAS!

Please see the associated publications:
https://www.biorxiv.org/content/10.1101/2020.12.30.424865v2
https://www.biorxiv.org/content/10.1101/2021.02.23.432573v1

Feel free to ask about questions, usage, etc, or to contribute.

All functions released, some documentation missing. Will be filling this in soon.