Retrieve Recent Patrons 
^^^^^^^^^^^^^^^^^^^^^^^

Adds a new library setting 'Number of Retrievable Recent Patrons' 
('ui.staff.max_recent_patrons') that specifies the number of recently
retrieved patrons that can be re-fetched from the staff client.

A value of 0 means no recent patrons can be retrieved.
A value greater than 1 means staff will be able to retrive multiple
recent patrons via a new Circulation 'Retrieve Recent Patrons' menu entry.

The default value is 1 for backwards compatibility.