Added game time to game world and time manipulation class. Users can increase and decrease game speed.

I was able to up to 10k * Speed before fps dropped below 60. Time moves pretty fast at 10k speed... If Dr. Coleman wanted us to implement a 'jump forward xxxxx days/hours/minutes' feature snapping the game speed up to a few k's for a second or so might be a nice way to do it. ofc the program would have to auto-reset to default speed once the target time is reached.