Add API doc

ShippingByRules_Framework_API.txt

+RulesShippingFramework:
+=======================
+
+
+API functions:
+~~~~~~~~~~~~~~
+  -) setup()                                                  // Used in the plugin's constructor
+  -) registerCallback($callback, $func)
+  -) warning($text, $args...)
+  -) debug($text)
+
+  -) parseRuleSyntax($rulestring, $countries, $ruleinfo)
+  -) checkConditions ($cart, $method)
+  -) getCosts($cart, $method)  // The central function to calculate the shipping cost
+  -) getRuleName($methodid)
+  -) getRuleVariables($methodid)
+
+  -) filterProducts($products, $conditions)                   // Used in the Rule's evaluateScoping
+
+  -) registerScopings($scopings)
+  -) getScopings()
+
+E-commerce specific functions (to be overridden in child classes!):
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  -) printWarning($message)  // $message already translated!
+  -) debug($message)
+  -) __($string)             // or use the translate callback for your own function!
+  -) getCustomFunctions()
+  -) addPluginCartValues($cart, $products, $method, &$values)
+
+  -) getOrderArticles($cart, $products, $method)
+  -) getOrderProducts ($cart, $products, $method)
+  -) getOrderDimensions ($cart, $products, $method)
+  -) getOrderWeights ($cart, $products, $method)
+  -) getOrderListProperties ($cart, $products, $method)
+  -) getOrderAddress ($cart, $method)
+  -) getOrderPrices ($cart, $products, $method)
+  
+  -) filterProducts($products, $conditions)                   // Used in the Rule's evaluateScoping
+  -) getMethodId ($method)
+  -) getMethodName ($method)
+  
+  -) setMethodCosts($cart, $method, $match, $costs)           // Potentially assign system-specific variables to the $method
+
+
+
+Callback functions:
+~~~~~~~~~~~~~~~~~~~
+  -) translate($message)
+  -) initRule($framework, $rulestring, $countries, $ruleinfo)
+  -) addCustomCartValues ($cart, $products, $method, &$values)
+