Enabled application restarts.

- Pressing Ctrl+Shift+F5 in the options menu restarts the game.  Beatmaps and sounds are not reloaded.
- Use GameContainer.setForceExit(false) to trigger a restart after exiting.

Other changes:
- Fixed general issues with track pausing/pause states.
- Store all background images loaded in OsuFiles in a static hash table, instead of in individual objects.  This allows easier access to the allocated memory.
- Only delete OSZ files if they were unzipped. (They were previously deleted in all cases.)
- Moved more images (mods, playfield, lighting) into GameImage.
- Moved OsuHitObject initialization inside Utils.

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

src/itdelatrisu/opsu/GameMod.java

@@ -23,22 +23,21 @@ import java.util.Collections;
 
 import org.newdawn.slick.Image;
 import org.newdawn.slick.Input;
-import org.newdawn.slick.SlickException;
 
 /**
  * Game mods.
  */
 public enum GameMod {
-	EASY          (0, "selection-mod-easy.png", Input.KEY_Q, 0.5f),
-	NO_FAIL       (1, "selection-mod-nofail.png", Input.KEY_W, 0.5f),
-	HARD_ROCK     (2, "selection-mod-hardrock.png", Input.KEY_A, 1.06f),
-	SUDDEN_DEATH  (3, "selection-mod-suddendeath.png", Input.KEY_S),
-	SPUN_OUT      (4, "selection-mod-spunout.png", Input.KEY_V, 0.9f),
-	AUTO          (5, "selection-mod-autoplay.png", Input.KEY_B);
-//	HALF_TIME     (, "selection-mod-halftime.png", Input.KEY_E, 0.3f),
-//	DOUBLE_TIME   (, "selection-mod-doubletime.png", Input.KEY_D, 1.12f),
-//	HIDDEN        (, "selection-mod-hidden.png", Input.KEY_F, 1.06f),
-//	FLASHLIGHT    (, "selection-mod-flashlight.png", Input.KEY_G, 1.12f);
+	EASY          (0, GameImage.MOD_EASY, Input.KEY_Q, 0.5f),
+	NO_FAIL       (1, GameImage.MOD_NO_FAIL, Input.KEY_W, 0.5f),
+	HARD_ROCK     (2, GameImage.MOD_HARD_ROCK, Input.KEY_A, 1.06f),
+	SUDDEN_DEATH  (3, GameImage.MOD_SUDDEN_DEATH, Input.KEY_S),
+	SPUN_OUT      (4, GameImage.MOD_SPUN_OUT, Input.KEY_V, 0.9f),
+	AUTO          (5, GameImage.MOD_AUTO, Input.KEY_B);
+//	HALF_TIME     (, GameImage.MOD_HALF_TIME, Input.KEY_E, 0.3f),
+//	DOUBLE_TIME   (, GameImage.MOD_DOUBLE_TIME, Input.KEY_D, 1.12f),
+//	HIDDEN        (, GameImage.MOD_HIDDEN, Input.KEY_F, 1.06f),
+//	FLASHLIGHT    (, GameImage.MOD_FLASHLIGHT, Input.KEY_G, 1.12f);
 
 	/**
 	 * The ID of the mod (used for positioning).
@@ -48,7 +47,7 @@ public enum GameMod {
 	/**
 	 * The file name of the mod image.
 	 */
-	private String filename;
+	private GameImage image;
 
 	/**
 	 * The shortcut key associated with the mod.
@@ -94,12 +93,12 @@ public enum GameMod {
 	/**
 	 * Constructor.
 	 * @param id the ID of the mod (for positioning).
-	 * @param filename the image file name
+	 * @param image the GameImage
 	 * @param key the shortcut key
 	 */
-	GameMod(int id, String filename, int key) {
+	GameMod(int id, GameImage image, int key) {
 		this.id = id;
-		this.filename = filename;
+		this.image = image;
 		this.key = key;
 		this.multiplier = 1f;
 	}
@@ -107,13 +106,13 @@ public enum GameMod {
 	/**
 	 * Constructor.
 	 * @param id the ID of the mod (for positioning).
-	 * @param filename the image file name
+	 * @param image the GameImage
 	 * @param key the shortcut key
 	 * @param multiplier the score multiplier
 	 */
-	GameMod(int id, String filename, int key, float multiplier) {
+	GameMod(int id, GameImage image, int key, float multiplier) {
 		this.id = id;
-		this.filename = filename;
+		this.image = image;
 		this.key = key;
 		this.multiplier = multiplier;
 	}
@@ -124,24 +123,17 @@ public enum GameMod {
 	 * @param height the container height
 	 */
 	public void init(int width, int height) {
-		try {
-			// create and scale image
-			Image img = new Image(filename);
-			float scale = (height * 0.12f) / img.getHeight();
-			img = img.getScaledCopy(scale);
+		Image img = image.getImage();
 
-			// find coordinates
-			float offsetX = img.getWidth() * 1.5f;
-			float x = (width / 2f) - (offsetX * SIZE / 2.75f);
-			float y = (height * 0.8f) + (img.getHeight() / 2);
+		// find coordinates
+		float offsetX = img.getWidth() * 1.5f;
+		float x = (width / 2f) - (offsetX * SIZE / 2.75f);
+		float y = (height * 0.8f) + (img.getHeight() / 2);
 
-			// create button
-			img.setAlpha(0.5f);
-			this.button = new MenuButton(img, x + (offsetX * id), y);
-			this.button.setHoverScale(1.15f);
-		} catch (SlickException e) {
-			ErrorHandler.error(String.format("Failed to initialize game mod '%s'.", this), e, false);
-		}
+		// create button
+		img.setAlpha(0.5f);
+		this.button = new MenuButton(img, x + (offsetX * id), y);
+		this.button.setHoverScale(1.15f);
 	}
 
 	/**
@@ -202,7 +194,7 @@ public enum GameMod {
 	 * Returns the image associated with the mod.
 	 * @return the associated image
 	 */
-	public Image getImage() { return button.getImage(); }
+	public Image getImage() { return image.getImage(); }
 
 	/**
 	 * Returns the mod ID.