Normalize (amplify) quiet audio, especially old SBD shows

[jcraigk]

See https://phish.in/1985-11-14 which is too quiet.

We may want to use https://github.com/bbc/audiowaveform or something similar and find the maximum volume on each track and use that to programmatically select tracks that are too quiet. Such tracks will likely need to be manually edited in a DAW and re-uploaded.

We could also use the audio data to identify long sections in tracks where volume does not get high, detecting encore breaks and other quiet sections that could be trimmed. If we took a moving average of volume and looked for >5 seconds where that value stayed below a certain threshold, that should do it.

There are also some soundchecks that are too loud and should be reduced overall.