Added score-viewing components to the song menu. [Completes 0bd72e7]

Added a scrollable score history area in the song menu.  Clicking on any score button will open the ranking screen.

Details:
- All drawing is performed by ScoreData.
- Store scores for the current focus node, and display up to "MAX_SCORE_BUTTONS" at a time; "startScore" is the starting index.
- When hovered over the score area, show scroll bar if needed.  When hovered over individual score buttons, change colors and show the rank.
- Scrolling with the mouse in the score area overrides song scrolling.
- Store scaled grade images as a Grade field.

Signed-off-by: Jeffrey Han <itdelatrisu@gmail.com>

src/itdelatrisu/opsu/Utils.java

@@ -18,6 +18,7 @@
 
 package itdelatrisu.opsu;
 
+import itdelatrisu.opsu.Scores.ScoreData;
 import itdelatrisu.opsu.audio.SoundController;
 import itdelatrisu.opsu.audio.SoundEffect;
 
@@ -198,6 +199,9 @@ public class Utils {
 		// initialize hit objects
 		OsuHitObject.init(width, height);
 
+		// initialize score data buttons
+		ScoreData.init(width, height);
+
 		// back button
 		Image back = GameImage.MENU_BACK.getImage();
 		backButton = new MenuButton(back,