This adds the ability to specify courier codes in transit and hold/transit slip templ...

This adds the ability to specify courier codes in transit and hold/transit slip templates via a %courier_code% macro and a lib.courier_code org unit setting.

So if an item at library BR1 is to be routed to library BR2, the org unit setting for BR2 is retrieved and that value is used for %courier_code%.

POSSIBLE TODO: Add simple interface-scoped caching for the courier code lookup (and perhaps for the mailing address lookup as well)

git-svn-id: svn://svn.open-ils.org/ILS/trunk@15315 dcc99617-32d9-48b4-a31d-7c20da2025e4