Need to manage shopping cart changes after multiship addresses selected

[lat9]

There are a couple of cases where the customer, after choosing multiple ship-to addresses for the cart's current contents, can make modifications to the cart that get "multiship" out-of-sync:

• Changing the quantity (either increase or decrease) via the shopping_cart page.
• Removing an item via the shopping_cart page
• Adding new products via an add-to-cart action or via a product-listing action.

[lat9]

Totally removing an item is currently handled; a product that is removed is simply removed from the multiship handling array, too.

[lat9]

The updates just committed cover adding a new product to the cart (all items ship to the customer's primary address) and updating a product in the cart (all additional items ship to the customer's primary address). There's still an issue when reducing the number of a product in the cart.

[lat9]

Included in v1.1.1.