Check to see if existing loan date is less than recall date

Check to see if existing loan date is less than recall date

It seems possible that a recall can be issued that actually extends
the loan period for an item with semester or other generous loan
periods. This adds a check for the current loan period and uses it
if the calculated threshold date is later.

Signed-off-by: Art Rhyno <art632000@yahoo.ca>
Signed-off-by: Dan Scott <dscott@laurentian.ca>