TODO

   1 For animation, moves should contains "moving" and "fading" maybe...
   2 (But it's really just for Magnetic chess)
   3 setInterval "CRON" task in sockets.js to check connected clients
   4 (every 1hour maybe, or more)
   5 Button to show all pieces that can move (next to expert mode; change icons)
   6 Style (crazyhouse): ghost image of reserve pieces are initially translated
   7 Some bots are very weak, others quite slow...