Displaying the active checkers on the board
merging changes
Changed Checker subclasses and powers

Changed the checker subclasses so that they will return a call to action
when a special power is used. This will require the full power
implementation to be handled by another class such as CheckerBoard or
Player.
brennan's changes
merging changes
getting the board display to work now that the board is actually an array of pointers
Merge branch 'gareth'
Merge branch 'zach'