Pylivestream

general internal quality improvements and bugfixes

no more .ini files. Each command requires a single JSON file. Suggest copying and editing from src/pylivestream/pylivestream.ini.

Python >= 3.7 should work, but Python >= 3.9 needed to run self-tests.

Use modern install without setup.cfg or setup.py, only pyproject.toml

scripts replaced with more robust `python -m pylivestream.screen` and similar

Apply Python >= 3.7 type annotation for quality/clarity. Add Python 3.7...3.10 to CI.

This affects Mac only.

A few months ago, we found we needed to add pix_fmt for screensharing on Mac. This was mistakenly also applied to files, which was incorrect. Now we apply manual pix_fmt only to webcam and screenshare.

May need future additional correction:

* what about OS 11 Big Sur? still needed for screenshare?
* also needed for Webcam?

remove /usr/bin/ffmpeg default from Linux--just look for FFmpeg. this avoids confusing error message when FFmpeg not installed, or installed elsewhere on PATH. Thanks to VanshCodes for reporting.

Thanks to foxtacles for fixing this bug introduced in v1.11.0, that made command line glob parameter be ignored