Build up a work library by writing a VHDL representation of the
package header into a source file. This representation needs to
be accurate enough that later invocations of vhdlpp can read them
with the VHDL parser.
Significant rework of scope management to unify the handling of
types in the ieee library and types/constants/components in packages.
This involved adjusting the parser rules to manage a stack of scopes
and rewriting the IEEE library support to not use global maps for
the loaded types.
This creates the Package class to represent packages, and the
Scope class to represent scopes in general. The library functions
are worked up to support scanning scopes for declarations that are
imported by "use" clauses.
Stephen Williams
Pawel Szostek