Apply a coupon to a manual order

We have a fair number of orders created by staff for customers, and want to use coupons to provide standard discounts for these customers ( resellers, actually ). I've implemented the ability to apply a coupon directly to an order in the order edit form:

- and order / edit pane for the coupon input form
- a JS callback to apply the coupon to the order
- a copy of uc_coupon that takes the order_id as the second param, loads the order instead of the cart, then loops through the order->products array to calculate the total discount.

It occurred to me while doing this that a) this might be useful to somebody else, and b) this could be made simpler by re-factoring uc_coupon_validate() to take either the cart contents *or* the order products as a param.

I realize you're already thinking about version 2; if this feature is interesting enough to you I could roll a patch against uc_coupon 1.x HEAD in the next week or so.