Code style cleanup from #12.

- Moved all curve-related classes into a new package.
- Added some fields and methods to Curve abstract class.
- Removed the old (no longer used) Bezier subclass.
- Changed Error throwing to ErrorHandler.error() calls.
- Formatted code.

Also fixed a crash when reaching the ranking screen with the "Auto" mod active.

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

src/itdelatrisu/opsu/states/Splash.java

@@ -148,7 +148,7 @@ public class Splash extends BasicGameState {
 			// close program
 			if (++escapeCount >= 3)
 				container.exit();
-	
+
 			// stop parsing OsuFiles by sending interrupt to OsuParser
 			else if (thread != null)
 				thread.interrupt();