mpd: Support playlists in browse
mpd: Support playlists in browse

Playlists are containers similar to directories. Treat them equally to
support playlists when browsing.

SuperStarPL/mopidy,priestd09/mopidy,hkariti/mopidy,mopidy/mopidy,swak/mopidy,jodal/mopidy,bacontext/mopidy,jcass77/mopidy,quartz55/mopidy,dbrgn/mopidy,vrs01/mopidy,quartz55/mopidy,ZenithDK/mopidy,bacontext/mopidy,mopidy/mopidy,bencevans/mopidy,glogiotatidis/mopidy,rawdlite/mopidy,jodal/mopidy,swak/mopidy,ali/mopidy,adamcik/mopidy,quartz55/mopidy,bencevans/mopidy,mopidy/mopidy,pacificIT/mopidy,jmarsik/mopidy,mokieyue/mopidy,ZenithDK/mopidy,vrs01/mopidy,liamw9534/mopidy,kingosticks/mopidy,vrs01/mopidy,ali/mopidy,swak/mopidy,mokieyue/mopidy,dbrgn/mopidy,bencevans/mopidy,ZenithDK/mopidy,jcass77/mopidy,woutervanwijk/mopidy,bacontext/mopidy,bencevans/mopidy,jmarsik/mopidy,rawdlite/mopidy,tkem/mopidy,diandiankan/mopidy,glogiotatidis/mopidy,ZenithDK/mopidy,adamcik/mopidy,swak/mopidy,SuperStarPL/mopidy,diandiankan/mopidy,diandiankan/mopidy,mokieyue/mopidy,glogiotatidis/mopidy,jodal/mopidy,mokieyue/mopidy,tkem/mopidy,dbrgn/mopidy,hkariti/mopidy,woutervanwijk/mopidy,bacontext/mopidy,quartz55/mopidy,priestd09/mopidy,kingosticks/mopidy,glogiotatidis/mopidy,pacificIT/mopidy,liamw9534/mopidy,hkariti/mopidy,jmarsik/mopidy,tkem/mopidy,kingosticks/mopidy,priestd09/mopidy,ali/mopidy,rawdlite/mopidy,dbrgn/mopidy,ali/mopidy,pacificIT/mopidy,tkem/mopidy,pacificIT/mopidy,jcass77/mopidy,hkariti/mopidy,SuperStarPL/mopidy,vrs01/mopidy,adamcik/mopidy,rawdlite/mopidy,SuperStarPL/mopidy,diandiankan/mopidy,jmarsik/mopidy