Cubyz-Assets 0.1.0

Create a bash script to compress the audio files automatically (#2)

@ikabod-kee I noticed that ffmpeg doesn't seem to like
`music/ikabodBTW/Intermission_I.ogg`. It gives me an error when I run
the recompression script. Do you have any idea what could be going on
there?

Also I would like to ask your opinion on bitrate. I read online
something about 128 kBit/s so I've chosen that for now.

remaining work:
- [x] copy over other assets
- [x] Create a CI step that automatically compresses and creates a
github release for use in the main repo

this also makes it possible to store other asset formats, including
unompressed and lossless.
fixes https://github.com/PixelGuys/Cubyz/issues/1834