V5.6: Fix shipping rate 0 without shipping= in the free plugin (already fixed in the advanced version)

V5.4: Fix evaluate_for_categories (order amounts calculated without quantities), Fix evaluate_for_manufacturers (wrong variable used); Fix protected warning

V5.1: Fix border case with shipping cost 0 being interpreted as non-existing due to php's behavior of the empty function

RegExp V1.0: Initial version of the RegExp vmshipmentrules plugin that provides five regexp-matching/replacing functions

Update the setCartPrices function to the latest code from VM3; change getShippingCosts to getValue, because not all rules are really shipping costs any more

Propapate the plugin to the rules
Make many functions protected in the rules
Cache the rules and the match for each method
Evaluate each rule only once
Prepare for scpoding functions and plugin API

Try to clearly separate the calculation between rule and plugin; Add plugin mechanism; implement modifiers