20111222
========


- Worked on new concept `TableRequest.subst_user`, needed for 
  :func:`lino.apps.dsbe.models.persons_by_user` to provide 
  links to :class:`lino.apps.dsbe.models.MyPersons` requests for *other* users.

- A little bug: TypeError "unbound method get_handle() must be called 
  with Persons instance as first argument (got ExtUI instance instead)" 
  in `reports.py`, line 615 
  when trying to return the choices for a ForeignKey to Person.
  Unit test :func:`lino.apps.dsbe.tests.dsbe_demo_tests.test14`.