Player: optionally use album gain for loudness normalisation

[skeller]

Add a new option "useAlbumGain" to optionally use album gain instead of track gain for loudness normalisation. This e.g. prevents loudness jumps in gapless mixes.

[devgianlu]

I am not entirely sure what is the proper use case for using the album gain. Does it make sense to use it globally or perhaps would it be better to use it when an album is being played?

[skeller]

Does it make sense to use it globally or perhaps would it be better to use it when an album is being played?

I use it globally, always. This is because I like to put e.g. the discography of a band/artist into a playlist and play that. So not only when playing a single album.

[devgianlu]

Sounds good to me!