Add a specification of Relation.Narrowed with supporting ClearDep
requirements from the Tenant and the SchemaDef.  Note that you don't
want to auto-clear the relationship when deleting a Table, because
you *want* integrity violation checks to occur during edits of a model.

Once the build is done, I'll modify the CFDbTest complex object tests
to make use of the new Narrowed specification, and verify that the
"Replace Complex Objects" test fails due to integrity violations.

After that I'll start working on the PostgreSQL rule support for
ClearDep.
Modify the CFBam 2.0 specification with ClearDep requirements
on the Tenant and SchemaDef.