Updated Main class with game loop and other methods necessary for game
wrapper to safely and properly control start up and exit of the
application.
Created the Main class. This class will run the game loop, provide
access to the game instance, return the FPS, allow the FPS to be
configured (possibly in game), call calculation and screen update
methods at specific intervals of time or every frame. This is very
configurable. This also enables the game to close safely, simply by
flipping a boolean value.