Use 'Album artist' instead of 'Artist' when grouping albums

[ghost]

Whenever an album has multiple Artists tags in its songs, Musique treats the album as separate records. For example, metatag imported from this MusicBrainz entry generates two "Keeper of the Seven Keys: The Legacy" in the album listing, one with songs tagged "Helloween" and one with the song tagged "Helloween feat. Candice Night". There is, though, a tag named Album artist where all songs are tagged "Helloween". MusicBrainz also has some albums with only the Album artist tag set, for example this one, which makes the album not being listed under the artist albums in Musique. I think it'd be smarter to prioritize Album artist and fall back to Artist when that tag cannot be found. 😄

[ghost]

On a related note, I tried building it to fix it myself and there's a missing header for the MacOS.

[flaviotordini]

Yes, this is a long standing issue. I'll look into it for a major release.