Loan Policy: Renew From Current Due Date *X Days Prior*

During prep for WOLFcon, Andrea noticed that you could check something out and, if you had selected Renew from = Current due date, you could immediately renew it. If you had a loan period of 3 months, you could immediately make it 6 or 9 (depending on the renewal limits in place).

Discussed with the SIG and they agreed that ideally you should be able to specify a number of days prior to the current due date at which time the renewal would be allowed. That said, many systems today don't offer this feature and people felt it wasn't a must-have for v1. Recorded in loan policy metadata document as well: https://docs.google.com/spreadsheets/d/1f8kX2mGub3ARPml4x3Ejaq1UsBeGP3xxLWbVk_DTgqg/edit#gid=0