[FEAT] Show bitrate for lossy audio files (lower priority)

[lekro]

Hello:

IMSLP should implement an average bitrate display for lossy audio files. (mp3, ogg, audio/video from mp4 if possible) This way, there could be low (128k) and high quality (320k/flac) versions of the same file and users could differentiate between those versions without having to add the bitrate in the description of the file. (For an example of where this could come in useful, see this page: http://imslp.org/wiki/Special:ReverseLookup/348495 )

Thanks.
Lekro