added shuffle button to UI + base data flow

backend/playbackengine.go

@@ -266,6 +266,15 @@ func (p *playbackEngine) GetLoopMode() LoopMode {
 	return p.loopMode
 }
 
+func (p *playbackEngine) SetShuffle(shuffle bool) {
+	p.shuffle = shuffle
+	//TODO: Implement functionality
+}
+
+func (p *playbackEngine) GetShuffle() bool {
+	return p.shuffle
+}
+
 func (p *playbackEngine) PlaybackStatus() PlaybackStatus {
 	stat := p.pendingPlayerChangeStatus
 	if !p.pendingPlayerChange {

backend/playbackmanager.go

@@ -354,6 +354,10 @@ func (p *PlaybackManager) LoadAlbum(albumID string, insertQueueMode InsertQueueM
 	return nil
 }
 
+func (p *PlaybackManager) GetShuffle() bool {
+	return p.engine.GetShuffle()
+}
+
 // Loads the specified playlist into the play queue.
 func (p *PlaybackManager) LoadPlaylist(playlistID string, insertQueueMode InsertQueueMode, shuffle bool) error {
 	playlist, err := p.engine.sm.Server.GetPlaylist(playlistID)
@@ -620,6 +624,10 @@ func (p *PlaybackManager) SetAutoplay(autoplay bool) {
 	}
 }
 
+func (p *PlaybackManager) SetShuffle(shuffle bool) {
+	p.engine.SetShuffle(shuffle)
+}
+
 func (p *PlaybackManager) Volume() int {
 	return p.engine.CurrentPlayer().GetVolume()
 }