Fix one-click moving with engine-define and wild-card pieces

Fix one-click moving with engine-define and wild-card pieces

In the disambiguation routine wild-card pieces were still treated as
special even when explicit moves were defined for them. In addition,
Disambiguate would try native XBoard piece motion for resolving ambiguous
moves, which is sensible for parsing SAN (which might be saved by an old
version of XBoard), but wrecks one-click moving.