Fast alist binding names of declared non-port names to anything.
These names can be the names of wires, instances, functions,
etc., that are in the local scope, for instance. Also includes
any items explicitly imported from packages.
Scopestack for lookup of global and package names. Note that this scopestack
doesn't typically contain the current module we're looking at,
because it isn't really a complete module until we add the implicit
wires to it.