Stream moves of a game

Stream positions and moves of any ongoing game, in ndjson. A description of the game is sent as a first message. Then a message is sent each time a move is played. Finally, a description of the game is sent when it finishes, and the stream is closed. Ongoing games are delayed by 3 moves, as to prevent cheat bots from using this API. No more than 8 game streams can be opened at the same time from the same IP address.