gtk: Only go to PLAYING with the next file if we were in PLAYING state before
gtk: Only go to PLAYING with the next file if we were in PLAYING state before

Otherwise setting a subtitle URI in PAUSED will automatically go to PLAYING.

amorenoc/gst-player,justinjoy/gst-player,codomania/gst-player,jabiers/gst-player,codomania/gst-player,shakin/gst-player,codomania/gst-player,JimmyOhn/gst-player,shakin/gst-player,shakin/gst-player,amorenoc/gst-player,sdroege/gst-player,jabiers/gst-player,amorenoc/gst-player,justinjoy/gst-player,amorenoc/gst-player,sdroege/gst-player,guiseco/gst-player,JimmyOhn/gst-player,guiseco/gst-player,JimmyOhn/gst-player,jabiers/gst-player,JimmyOhn/gst-player,amorenoc/gst-player,sdroege/gst-player,guiseco/gst-player,sdroege/gst-player,codomania/gst-player,justinjoy/gst-player,JimmyOhn/gst-player,sdroege/gst-player,codomania/gst-player