End victory flash on new game and restart game.

End victory flash on new game and restart game.

Net provides the best demonstration of why. Complete a game of net,
then press N while the victory flash is playing: then the victory
flash keeps playing on the new game board. (Tip: save a game which
but for a redo is completed, then you can reproduce this repeatedly
without having to complete a new game each time.)

The flash timer reset code is placed together with the animation
timer reset code, because the two are conceptually related. Note
that midend_restart_game resets animations via midend_finish_move.