Added a beatmap cache database.

- New database ".opsu.db" stores a cached copy of all parsed beatmaps.  All data will be read from this database unless the last modified time of a beatmap file does not match the one in the table.
- OsuParser inserts all new entries to the database in batch after parsing.
- Added *toString()/*fromString() methods for 'breaks', 'timingPoints', and 'combo' fields in OsuFile for use with the database.
- For any database format changes, update the DATABASE_VERSION field in OsuDB.
- Reloading beatmaps (F5) will now clear the beatmap cache.

Related changes:
- Added small DBController class for convenience.
- Changed 'bg' field of OsuFile to only contain the image file name, instead of the full path.
- Deleted printDatabase() method from ScoreDB.

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

src/itdelatrisu/opsu/states/Game.java

@@ -28,13 +28,13 @@ import itdelatrisu.opsu.Options;
 import itdelatrisu.opsu.OsuFile;
 import itdelatrisu.opsu.OsuHitObject;
 import itdelatrisu.opsu.OsuTimingPoint;
-import itdelatrisu.opsu.ScoreDB;
 import itdelatrisu.opsu.ScoreData;
 import itdelatrisu.opsu.Utils;
 import itdelatrisu.opsu.audio.HitSound;
 import itdelatrisu.opsu.audio.MusicController;
 import itdelatrisu.opsu.audio.SoundController;
 import itdelatrisu.opsu.audio.SoundEffect;
+import itdelatrisu.opsu.db.ScoreDB;
 import itdelatrisu.opsu.objects.Circle;
 import itdelatrisu.opsu.objects.HitObject;
 import itdelatrisu.opsu.objects.Slider;