Changes:
* Change tz check from "NYC"
* Ignore empty datasets in rt.hstack
* Fix incorrect results from searchsorted
* Fix error on loading multi-Cat column from SDS file
* Replace Documentation email link with template
* Point public docs to riptable.readthedocs.io/en/stable
* Pin sphinx-autoapi and astroid
* Doc: Fixes comments, and breaks lines
* Pin to riptide_cpp>=1.15.1
* Doc: Updates CONTRIBUTING.md