Pystow

Bug fix - don't keep untarring it

Add ensure_untar function to get and unzip a tar archive

- Fix bug in ensure_tarfile_csv about sep
- Fix mypy to automatically install types
- Add tar xml processor

Add more CLI functions and update docs

- Unify interface for download functions (normal, google, and S3)
- Add hash checking functionality to download() and download_from_google() (https://github.com/cthoyt/pystow/pull/7; thanks mberr )

Fix bug in google download - now uses consistent session