Implemented menu with three buttons that light up when hovering over and bring you to the destination when clicked on. Buttons are Play, Exit and Info (NYI). Pressing the Enter key also triggers Play and the Escape key triggers Exit. Pressing Exit while playing pauses the game, makes everything turn to a 50% opacity and make all functionalities stop (so you can't move, jump, timers don't update, etc. but your characters is drawn). Moved key handling to Player class.
(Temporarily) solution for crash happening at player <-> gameobject collision.