Added pausing and ability to block all screens below from updating
Changed screens HandleEvent, Update and Draw functions to use the base calss method

Signed-off-by: BunnyRabbit2 <iamlewisstorey@yahoo.com>
Added MenuScreen and MenuBG content
Will be used to explain controls and stuff

Signed-off-by: BunnyRabbit2 <iamlewisstorey@yahoo.com>
Added text to MenuScreen and ability to move onto the game
Added OpenSans font and licence for it
Setting up the text is a bit funky and probably wrong but it works

Signed-off-by: BunnyRabbit2 <iamlewisstorey@yahoo.com>