remove xrefs

vestigial remains of testing?
refactor tokenizing the xrefs

move tokenizing to LoadEntities.
finish refactor xrefs

See previous commit.
fix typo in TestClassA

It was being caught as an external ref. Nice.
Recurse on the catalog entities (part I)

So catalog entities can refer to each other.
Recurse on catalog entries (part 2)

almost there, just need to tweak KeyElements.