Modified database and contribution to allow a product to be marked as only available for sale as part of a bundle. While this could be accomplished by turning the product status red, the customer would then not be able to view the details of the product if they clicked on that product name while viewing the bundle that contains it.

All add to cart buttons are now disabled if the product is sold only in a bundle or if it is out of stock and purchasing of out of stock items is prohibited including the one in products_new that was previously missed by this contribution. Checks have also been added to stop checkout if a "bundle only" product was added to a shopping cart prior to being marked as not for separate sale.

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