Added some new UI stuff
In this update I have added two new user interface components: pause indicateor and game over display
I also implemented the ability to pause the game by pressing 'p'

At this point in time there are currently two bugs which will need to be fixed before I cna declare this project finished:
- Phantom Rotation: This is a problem I have noticed a long time ago, it is to do with the use of static variables and I should be able to fix it relativly easy.
- Crash on End: Sometimes the game will crash when you end becuase a tetrimino manages to be created without a parent object