There is now an implicit $unit package that needs to be ignored by
the blif target. Take this opportunity to make the root module checking
for the blif target a bit more robust.
The signal bit numbering should be used for signals. This is
necessary for .model ports because the user specified numbers
are part of the interface, but once that is done, it is trivial
to follow it internally as well.
Stephen Williams
Cary R
Larry Doolittle