Added unit tests for Entity class.
Moved construction code out of model code.
Added Javadoc for addCell code.
Added class to load a Map or create a new one.
Adjusted unit tests to work with changes to Map constructor.
Added unit tests for Jdig class.
Added unit tests for Map class.
Changed visibility of load method.
Fixed a bug that was causing getAdjacentCell to return the wrong cell.
Moved construction code to new class.