Delete Payment Method

This is semi-deliberate. I'm creeped out by the notion of deleting transactions, or any payment method/payment form that has been part of a transaction, because of the referential and tracking implications.

However, I agree that it should be minimally possible to disable methods and forms so that they disappear from view. Perhaps it's also fair to delete a method or form that has never been used at all.

Patches welcome!

In Drupal 7, It's now possible to disable a payment_method (if it has transactions) or delete it (if it doesn't)