in structural contexts, Replace vector<PExpr*>
and list<PExpr*> with svector<PExpr*>, evaluate
constant expressions with parameters, handle
memories as lvalues.
Parse task declarations, integer types.
location of things. PGate, Statement and PProcess.
elaborate handles module parameter mismatches,
missing or incorrect lvalues for procedural
assignment, and errors are propogated to the
top of the elaboration call tree.
Attach line numbers to processes, gates and
assignment statements.