First attempt at the game engine and rules/specs

* Intended to outline the rules needed to implement a minesweeper game.
* Possibly over-engineered.
* Uses native (hopefully modern) JS, so may not be compatible with some
browsers.
* Attempted to code in such a way where the UI would need absolutely no
knowledge of the game.
* Unsure if this approach is really possible for a dojo, or maybe I'm
just a slow coach!