Use price types for the price alter handler. Clone the node object, so that the discounts don't interact with each other on the attribute option lists. Likewise, add the price info to the price cache key.

#462944 by Island Usurper: Differentiate between different items in the cart when caching discounted prices.
Load the user account for order discounts. Clarify which user account (current or order's) in the trigger documentation.

Set default values on action form.

Initial commit.