Define 11x17+16_chu as alias for Wa Shogi

Define 11x17+16_chu as alias for Wa Shogi

Under the WinBoard 'Alien Edition' Wa Shogi has to be played as a variant
of Chu Shogi with modified board size. To accomodate the holdings, the
board must be 11x17, and needs the extra ranks blacked out. We thus added
11x17+16_chu as a duplicat of crazywa. The blacked-out ranks will appear
in the FEN of a setboard command as asterisks, so the FEN reader had to
be made to ignore these.