Fix bug that causes the gravity to be carried over to new games.
Remove the overriding of the toString() method to make debugging easier.
Remove the limit on the number of highscores written to file.
Fix a few leaderboard bugs. Remove sort() as it became unnecessary after the fixes.
Fix gravity not being reset on restart.
Fix a bug that caused the leaderboard to display 6 names. Fix bug
that caused scores to be compared to the highest score instead of
the lowest.
Prepare the existing code for colour support.