Tweenable Text, Player + Camera end level acting

Tweenables now inherit from the TweenableElement class. Implementing
tweenable sf::text on top of this.
Can get the screenspace offset vector directly from the camera now.
Added some logic to allow locking the player into one input state and
not accept other player inputs.
Game detects collision between player and end of level rect, then locks
the camera and locks the players input state to walk off the screen.