checkpoint
added nice little uml diagram of the whole shebang
Logic now checks if players can move at all, calls game over if not

added subclass of DefaultEdge (from jgrapht) to expose vertices
Board:
    - added method hasUnoccupiedNeighbour() as part of motility check
Logic:
    - fixed logical error in advancePhase()
    - reorganized advancePhase()
    - added method movingStillPossible() as part of motility check
    - changed return type of removeStone() to int
Stone:
    - added method canMove() as part of motility check

test/FullGame: fixed tests to correspond to change in method return types
motility check now works

test/FullGame has been updated to include the check
Checkpoint
Checkpoint
fixed merge errors in Head
checkpoint