Extend the Jigoshop shipping methods by adding a basic weight method.
Fixed calculation bug if level is reached precisely, including a >= calculation in php
Added an other level before the existing ones for letter weight and letter sending price
Modified the calculation part to include vat calculation on shipping fees (with option to enable this calculation or to disable it
Added Handling fee field and calculation of shipping total
Deactivated backwards compatibility to Jigoshop versions prior and included 1.4