Adsbcot

Happy Summer Solstice!

- Rewrote GitHub actions, moved most logic to shell script and Makefile.
- Renamed Debian package from python3-adsbcot to adsbcot.
- Standardized Makefile for all PyTAK based programs.
- Cleaned, simplified and expanded documentation.
- Created Makefile jobs for Debian packaging and PyTAK customization.
- Moved all media to media sub directory under docs/.
- Converted README.rst to README.md.
- Style & Linting of code.
- Removed support for Python 3.6.
- Removed support for DUMP1090_URL configuration parameter.
- Added Debian service: /lib/systemd/system/adsbcot.service
- Added Debian conffile: /etc/default/adsbcot
- Added Debian postinst with service config, debug and startup instructions.
- Added with_asyncinotify as an optional extra.

- Fixes 42: ADSBCOT CoT Events are not showing up in iTAK.

- New for 2024!
- Fixed formatting of CHANGELOG.md
- Fixes 28: COT_STALE in documentation.
- Fixes 31: Debian package build is broken.
- Fixes 37: Move RTFD docs over to Markdown.
- Fixes 38: Don't discard ImportError exception.
- Fixes 39: Move CoT generation to PyTAK's `gen_cot_xml()` function.
- Fixes 40: Add CoT `access` attribute.

Added optional altitude filters: ALT_UPPER, ALT_LOWER:
- ALT_UPPER: Upper Altitude Limit, geometric (GNSS / INS) altitude in feet referenced to the WGS84 ellipsoid.
- ALT_LOWER: Lower Altitude Limit, same ref as ALT_UPPER.

Improved support for AirTAK.
- Added a Read the Docs documentation site: https://adsbcot.readthedocs.io
- Added ability to read file:// URLs, including reading aircraft.json from local fs.
- Replaced setup.py metadata with setup.cfg.
- Code cleanup.

- Fixed 17: Incorrect course/track for some dump1090 feeds. Thanks dnlbaldwin
- Code cleanup.