Add Linux support

[AlbrechtL]

This pull requests add Linux support by using mono.

• Audio decoding is done by ffmpeg instead of NAudio
• Switch to .net 4.8 (necessary for Xabe.FFmpeg)
• Add support for OGG, WMA, WAV files (only for Linux)
• Add sorting of input files to alphabetical order (only for Linux)
• Add Linux section to README.md
• Add Linux start script

Test binaries can be found here: https://github.com/AlbrechtL/teddy/releases/tag/v1.2.4-linux_2

[Mahelita]

Great! Now I can ditch my Windows dev evaluation virtual box. Thanks!

[g3gg0]

can you check if it works with the Costura package?
Is it still alpha or considered beta already?

[AlbrechtL]

can you check if it works with the Costura package?

According to this side https://github.com/Fody/Costura Costura is obsolete and I don't see Windows Forms support. So I expect that it will not work.

Is it still alpha or considered beta already?

I'm using it when I create new music tokens. Unfortunately the mono Windows Forms implementation is really buggy. So I would say that it is usable but only for people that don't have Windows.

[marc4s]

could there be two branches - one for linux one for windows ? I would like to see actually linux builds as well. how complicated would be the proxmark support for linux?