Fixed error handling issues in the game container. (#218)

This makes error catching generally more robust. Catch all exceptions in start() loop, catch close_sub() exceptions separately, and suppress linked errors (so the root exception should actually get captured).

Also fixed null pointers in methods called by close_sub().

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

src/itdelatrisu/opsu/ui/Cursor.java

@@ -281,8 +281,6 @@ public class Cursor {
 
 		// reset angles
 		cursorAngle = 0f;
-		GameImage.CURSOR.getImage().setRotation(0f);
-		GameImage.CURSOR_TRAIL.getImage().setRotation(0f);
 	}
 
 	/**