Add an event posting on track change notification

This event should be helpful for implementing a Last.FM API into the
player once again.

Signed-off-by: Christopher Snowhill <kode54@gmail.com>

Application/PlaybackController.m

@@ -32,6 +32,8 @@ NSString *CogPlaybackDidPauseNotficiation = @"CogPlaybackDidPauseNotficiation";
 NSString *CogPlaybackDidResumeNotficiation = @"CogPlaybackDidResumeNotficiation";
 NSString *CogPlaybackDidStopNotficiation = @"CogPlaybackDidStopNotficiation";
 
+NSString *CogPlaybackDidChangeTrackNotification = @"CogPlaybackDidChangeTrackNotification";
+
 @synthesize playbackStatus;
 
 @synthesize progressOverall;
@@ -621,6 +623,19 @@ NSDictionary *makeRGInfo(PlaylistEntry *pe) {
 		[self removeHDCD:nil];
 	});
 
+	if(playlistController.currentEntry) {
+		NSDictionary *info;
+		if(pe) {
+			info = @{ @"previous": playlistController.currentEntry,
+				      @"playPosition": @(playlistController.currentEntry.currentPosition),
+				      @"current": pe };
+		} else {
+			info = @{ @"previous": playlistController.currentEntry,
+				      @"playPosition": @(playlistController.currentEntry.currentPosition) };
+		}
+		[[NSNotificationCenter defaultCenter] postNotificationName:CogPlaybackDidChangeTrackNotification object:info];
+	}
+
 	if(pe) {
 		[[NSNotificationCenter defaultCenter] postNotificationName:CogPlaybackDidBeginNotficiation object:pe];
 	}