Update GStreamer software mixer to use new output API
Update GStreamer software mixer to use new output API

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