-Add Agent class, intended to be base class for all potential agents.
These include automatons or humans, via either console or some ui
mechanism.
-Refactor board related code to board class. As the 'design' of this
(admittedly simple) project grew, I sensed a need to impose more
intuitive locations for items. This is contrived, as I knew this would
happen, but often it is important to reduce code bloat to keep things
slim, and only when there is a need make the design more complex rather
than upfront engineer something that will never be used.