playlist: Add classes for track collections
playlist: Add classes for track collections

jodal/pyspotify,jodal/pyspotify,felix1m/pyspotify,kotamat/pyspotify,kotamat/pyspotify,felix1m/pyspotify,kotamat/pyspotify,felix1m/pyspotify,mopidy/pyspotify,mopidy/pyspotify,jodal/pyspotify