Some documentation updates
Added check_rows_partially

for an nxn matrix, look through the row positions for almost
n_in_a_row's (n spaces lined up, where n-1 of them have been played on by
the same player, and the last one is empty. In other words, a situation
where a player could potentially win on their next turn). Then note these
positions, and the potentally winnning player, down on the
given n_in_a_row_position_matrix.
Merge branch 'master' of https://github.com/masnes/tic_tac_toe_ai