More graphical updates, some code cleanup, and minor fixes.

- The MenuButton class now fully supports hover effects (scale, fade, rotate) for Animations.
- Used a fixed location for the selection buttons in the song menu (previously based on the "back" button width, which varies widely in different skins).
- Added hover effects for "retry" and "exit" buttons in the ranking screen.
- Changed animation speed of back/skip buttons.
- Fixed a bug where main menu showed the incorrect number of songs loaded during searches.
- Removed unneeded draw() methods in Utils for color filters (since 69f5aa5).
- Moved Utils.drawCentered(Image, ...) into the Image class.
- Added overwritten Image class to Maven excludes.

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

src/org/newdawn/slick/Image.java

@@ -556,7 +556,7 @@ public class Image implements Renderable {
 	}
 	
 	/**
-	 * Draw the image based on it's center 
+	 * Draw the image based on its center 
 	 * 
 	 * @param x The x coordinate to place the image's center at
 	 * @param y The y coordinate to place the image's center at
@@ -564,6 +564,17 @@ public class Image implements Renderable {
 	public void drawCentered(float x, float y) {
 		draw(x-(getWidth()/2),y-(getHeight()/2));
 	}
+
+	/**
+	 * Draw the image based on its center with a color filter
+	 *
+	 * @param x The x coordinate to place the image's center at
+	 * @param y The y coordinate to place the image's center at
+	 * @param color The color filter to apply
+	 */
+	public void drawCentered(float x, float y, Color color) {
+		draw(x - (getWidth() / 2f), y - (getHeight() / 2f), color);
+	}
 	
 	/**
 	 * Draw this image at the specified location