Support identifiers for predefined types and exceptions
Add test output to .gitignore
Add a couple of class examples to the coverage test
Fix bug in handling of functors
Fix bug in handling of classes and class types

Now adds all four identifiers associated with a class to the
environment.
Don't use element references if the reference is resolved
Fix lookup priority of signature item references in cmis
Fix bug with labelled arguments
Ignore empty polys in cmti types