Bug 14395: Code changes

Bug 14395: Code changes

This patch updates the calculation of 'No renewal before' to include the
new syspref NoRenewalBeforePrecision.

To test:

1) Check out an hour-based loan with 'No renewal before' set to 1.
   Switch syspref NoRenewalBeforePrecision between 'date' and 'exact
   time'. Confirm that with both settings the item cannot be renewed
   until exactly one hour before due.

2) Check out a day-based loan with 'No renewal before' set to 1 day.
   Confirm that:
   * with NoRenewalBeforePrecision set to 'date', renewal is possible
     at 12:00 AM on the day before due.
   * with NoRenewalBeforePrecision set to 'exact time', renewal is
     possible at 11:59 PM on the day before due.

Sponsored-by: Hochschule für Gesundheit (hsg), Germany
Signed-off-by: Jesse Weaver <jweaver@bywatersolutions.com>