winning condition for the columns
should end when left diagonal is a winner
complete board sweep for win
check board for win refactor
should be able to set a player on the board
get the number of pieces on  the board
should know if a spot is vacant
rename boardinpl to boardimpl
move the responsibility of sweeping the board for a win to the board

move the responsibility of sweeping the board for a win to the board

move the responsibility of sweeping the board for a win to the board
should be able to tell if a game is a draw