Add back support for restarting the current track.

src/main/java/moe/nekojimi/chords/QueueManager.java

@@ -26,6 +26,8 @@ import java.util.function.Consumer;
  */
 public class QueueManager implements Consumer<Song>
 {
+
+    private Song restartingSong = null;
     private final Queue<Song> jukeboxQueue;
     private Playlist playlist;
     private MusicHandler handler;
@@ -52,6 +54,13 @@ public class QueueManager implements Consumer<Song>
      */
     public Song nextSongNeeded()
     {
+        // if we're restarting the current song: store, clear, and return it
+        if (restartingSong != null)
+        {
+            Song ret = restartingSong;
+            restartingSong = null;
+            return ret;
+        }
         // if there's anything in the queue, play that first
         if (!jukeboxQueue.isEmpty())
         {
@@ -118,6 +127,12 @@ public class QueueManager implements Consumer<Song>
 
     public boolean restartSong()
     {
-        throw new UnsupportedOperationException("Not supported yet.");
+        restartingSong = handler.getCurrentSong();
+        if (restartingSong != null)
+        {
+            handler.playNext();
+            return true;
+        } else
+            return false;
     }
 }