Restrict music to a sample rate of 48 kHz

[IntegratedQuantum]

Right now I think we have a mix of 44.1k and 48k, and it is not clear if songs of different sample rates exist.

[ikabod-kee]

48k is the standard for video games nowadays, so I think that'd be good.

[IntegratedQuantum]

Alright let's do this then. I will also adjust the base game to run on 48 kHz, please ask the artists of existing songs to reexport their music in 48 kHz, so we don't lose any quality doing the conversion ourselves.