The intranet item display provided by moredetail.pl
would display the original due date of the item, and
would thus be incorrect if the item had been renewed
and got a different due date.

The incorrect date was coming from items.onloan,
which AddIssue() sets to the due date.  This patch
fixes the bug in two ways:

[1] AddRenewal() now updates items.onloan with the
    correct due date.
[2] Two templates were updated to display the
    due date from (indirectly) issues.date_due
    instead of items.onloan, thus making it less
    likely that the wrong value will be displayed.

This patch does *not* update items.onloan to reflect
the correct due date.

Signed-off-by: Galen Charlton <galen.charlton@liblime.com>