Othello

Othello is a game played on a square board, with black and white pieces. If a white/black piece is surrounded by a  black/white one (either left/right or up/down) then the piece will change color. Players play in turn until they have valid moves left. Implement Othello following Object Oriented criteria (e.g. what is a piece, what is a board, what is a game, who keeps the score, what is a valid move).