For animation, moves should contains "moving" and "fading" maybe...
(But it's really just for Magnetic chess)
setInterval "CRON" task in sockets.js to check connected clients
(every 1hour maybe, or more)
Systematically show init+dest squares in PGN, maybe after short notation
(2 moves list, second for de-ambiguification)
Crazyhouse: keep track of promoted pawns.