Previously: matching of blackbox pins was enforced
by using pin names for passive nets in the compare.
Problem: no match was achieved when pins are not
named or not named consistently.
In this case, it's desirable to treat them as
ambiguous.
The new solution is to let the ambiguity resolver handle
that using an extended definition of the net names:
it will take the pin name into account if an unnamed net
is attached to a pin.
In addition, net ambiguities are projected to pin
equivalence now. This also will propagate symmetry
through nested blocks (dbNetlistCompareTests:20_BusLikeConnections).