removes unused setAlwaysQueen method from Board widget
removes unused chess Piece require from Board
implements move animation in Board and adds move method.

also removes old enable/disableHtmlUpdates methods, as they weren't used anywhere.

adds animateMove method, along with move, which both take Move-like objects.
(move is mainly to make the interface consistent - it just uses setBoardArray)

calling setBoardArray now cancels the current animation if there is one,
so there shouldn't be any problems with keeping it consistent.
fixes RematchOffered firing in Game - sends colour
removes redundant check in SeekForm (seek ? .. : .. when already within if(seek))
implements new game/cancel on GamePage - uses same mechanism and animation system as SeekForm

there is duplication in the button style and the expiry time calculations,
but factoring it out seems too far for now.

the seek form on the homepage updates as appropriate when the user creates
a new seek from the gamepage.  if the user creates a new seek from the seek
form with the same time options as a gamepage, the game page will update as
though the new game button had been pressed.