Show last positive score delta.

[yarcat]

I think this is awesome idea! I think we have to extend score listener to receive this information, and it also has to know where to draw the thing. Due to that, I believe, we have to extend listener interface to the following:

   void onScoreChanged(ScoreChangedEvent event);

   // Later we can extend this and produce some sounds.
   public ScoreChangedEvent {
      // Current value of the score.
      final String newScore;
      // Last delta to display (e.g. +5).
      final String scoreDifference;
      // Compound reference to calculate coordinates for the bubbles.
      final CompoundReference ref;
   );

Wdyt?

[soulne4ny]

I just got an idea that it would be helpful to see score change in the log.