TODO

   1 Fix rescaling by adopting a different strategy: use mouse scroll instead, +/- 5% each time ?
   2 Seems easier to control width/height accurately and safely in this way...
   3
   4 Impossible to play / triple move in Doublemove : turn issues, maybe because a move is sent twice to the server...
   5 => solution = sign (hash?) moves, and if an already received signature received again, ignore?
   6
   7 add variants : Chakart first (dark,cylinder)
   8 Dark Racing Kings ?
   9 Checkered-Teleport ?
  10
  11 Otage, Emergo, Pacosako : fonction "buildPiece(arg1, arg2)" returns HTML element with 2 SVG or SVG + number
  12 réfléchir aux animations par variante (reversi, Chakart, Atomic, ...)