more work on variant switch

more work on variant switch

the previous solution to the cosmetic problem of displaying a wrong shuffle
in an ICS game that was observed from the very start unfortunately turned
out to cause a real error in diplaying a stored game through the smoves
command, for variants not using the FIDE setup as standard.

This patch displays the position from before setting up the start position
of the new variant, but does setup boards[0] to the initial position of that
variant. (If this is a wrong shuffle, it is thus ot displayed, and a new board
will immediately be sent from the ICS to correct the shuffle.)