Add metadata keys for MB Release ID and MB Release Group ID
A MusicBrainz release represents the unique release (i.e. issuing) of a product on a specific date with specific release information such as the country, label, barcode and packaging.
A release group is used to group several different releases into a single logical entity.
Add Grilo Media support for MusicBrainz release and release group identifiers.
Deprecate use of album identifier since it could mean release or release group id.
Edited by Sumaid