PlaybackManager: add Iterator getter (for cursorIterator, #21)

src/Playback/PlaybackManager.ts

@@ -51,6 +51,9 @@ export class PlaybackManager implements IPlaybackParametersListener {
     private audioPlayer: IAudioPlayer<any>;
     private musicPartManager: MusicPartManager;
     private cursorIterator: MusicPartManagerIterator;
+    get Iterator(): MusicPartManagerIterator {
+        return this.cursorIterator;
+    }
     private playbackIterator: PlaybackIterator;
     //private Dictionary<int, MidiChannelInfo> instrumentsPerMidiSoundDict = new Dictionary<int, MidiChannelInfo>();
     //private Dictionary<int, int> midiSoundToChannelMappingDict = new Dictionary<int, int>();