Finished porting Engine code from IvoryHammer
Added stuff to GameScreen needed to compile
NOT YET TESTED

Signed-off-by: BunnyRabbit2 (Lewis Storey) <iamlewisstorey@yahoo.com>
Added cleanup code to the engine

Signed-off-by: BunnyRabbit2 (Lewis Storey) <iamlewisstorey@yahoo.com>