v1.7.1: Marking Shipping costs option as experimental

Marked "Full shipping calculation" option as experimental - lots of rewrite is needed, to make it work as it should. It also require large amounts of time and memory if used.

Coding standards

If a product had combinations, the reference of these where not exported correctly.
Fixed a bug regarding multishop and if a product was active or not in the specific shop.

In all a lot of fixes have been added