Support for multiple tags

[Sébastien Bertrand]

Decibel should support multiple tags in a song, for example a song could have the following tags :
  - artist: artist1
  - artist: artist2
  - title: title
  - genre: genre1
  - genre: genre2
  - album: album

If I open this song with ExFalso or Quod Libet, they display each tag correctly (for exemple in the "artist" column, they display: "artist1, artist2"). But Decibel doesn't. I think it would be nice to correct this.

Thanks for everything.

[Sébastien Bertrand (damocles)]

I join an example file of what I describe in this bug. The metadata of this file contains two artist's fields (and so on).