Refactoring/ Performance optimisation/ better configuration Options

[CommanderStorm]

Performance:

• [x] convets 200MB of downloaded video in 12 Minutes into 150MB auto-edited video

Code-Quality:

• [x] plus-string -> f-string
• [x] set -> typing.Set
• [x] spawining loads of processes-> ProcessPool-ExecuterService
• [x] yt-download->ffmpeg for speed and dependency reasons

Other changes:

• [x] created Readme
• [x] moved dependency management into different file
• [x] added a "configuration system" where you can check what lectures you want to be downlowaded

Caveats:

• I have not tested this on a pi, as I don't have access to such a device.
• PROCESS_COUNT assumes that there are enough system recources availible. I have no idea how realistic this is.