OandX: Game example code

The example demonstrates simple O and X (or zero and cross) game. It has the controller and the engine. This controller uses instructions from the user to update the engine (board.) while the engine implements the game logic.

The engine with the class name CoandXEngineprovides the logic for new game by marking every tile blank and logic for making the move. Also persists the controller’s state whose turn it is, and which symbol the local player is using.