Make Board.safePlacesFor package-private
Document Board.placeWithoutConflict
Add PieceKind.toString
Add Position.toString method
Add Piece.toString
Add Board.toString
Add specs for findSafePlacement without any piece kinds
Add spec for number of boards generated by findSafePlacement with a single piece
Add spec for findSafePlacement containing one piece on each board when giben one kind
Add spec for the kind of a single piece in results of findSafePlacement
Add spec for findSafePlacement's boards containing as many pieces as many kinds as were given
Add spec for findSafePlacement not containing duplicates
Add App object