tweaks

[2bndy5]

• add type hinting
• ran black
• adjust CI
• upgrade docs theme and move all docstrings into glidepoint.py src
• ran spell check
• update docs' ToC for API reference and landing page
• report() converted to read() in favor of using the new available() - all of which only relate to Relative or Absolute modes (not AnyMeas mode)
• clear_flags() renamed to clear_status_flags()
• switch to pre-commit for linting tools (mypy pylint, black)
• switch to pyproject.toml instead of setup.py; the setup.py module still exists (as a proxy to pyproject.toml) until it is no longer needed.