Fix filtering used by the 'D' command, and a few other activities that
allow both object class filtering and bless/curse state filtering, so
that when both class(es) and state(s) are specified, objects need to
match both rather than either. D?C will present the player with cursed
scrolls to drop rather than all scrolls plus all other cursed objects.
This also fixes another instance when gold could end up with its bknown
flag set.
b4741d6206