Fixed a null pointer exception. (blame: 92f4a51)

This occurred when inserting beatmaps with null "bg" field into the database.

Also moved LOAD_HD_IMAGES option from "Custom" tab to "Display".

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

src/itdelatrisu/opsu/beatmap/BeatmapImageCache.java

@@ -63,7 +63,7 @@ public class BeatmapImageCache {
 
 	/**
 	 * Returns the image mapped to the specified beatmap.
-     * @param beatmap the Beatmap
+	 * @param beatmap the Beatmap
 	 * @return the Image, or {@code null} if no such mapping exists
 	 */
 	public Image get(Beatmap beatmap) { return cache.get(beatmap.bg); }