20120529
========

The `id_card_no` field in :class:`lino.modlib.cbss.models.SSIN`
had a `max_length` of 10. That was not enough. Now it's 20.


Fixed internal bug ClearCacheAction.get_permission order of arguments.

:mod:`lino.modlib.debts`:
:class:`Actor <lino.modlib.debts.models.Actor>` and
:class:`Entry <lino.modlib.debts.models.Entry>`
now have a :attr:`lino.core.model.Model.allow_cascaded_delete`.


:class:`Entries <lino.modlib.debts.models.Entry>`
(and in fact all subclasses of :class:`lino.mixins.Sequenced` )
now have a new action `insert_before` which duplicates
the current row, inserting it before the current one.

Row actions defined on a model using `@dd.action` didn't yet work.
Changed argument order for calling RowAction.run().
There are three methods for defining actions:

- On the Table::

    class ParticipantsByCourse(RequestsByCourse):
        ...
        @dd.action(_("Unregister"))
        def unregister(obj,ar):
           ...

- On the Model::

    class Sequenced(models.Model):
        ...
        @dd.action(_("Insert before"))
        def insert_before(self,ar):
            ...

- As a separate class::

    class ClearCacheAction(actions.RowAction):
        ...
        def run(self,obj,ar):
            ...

    class Foo(models.Model):
        ...
        do_clear_cache = ClearCacheAction()



New action "Duplicate" on `debts.Budget`. Doesn't yet copy actors and entries.