Add WArning=..., Error=..., Notice=..., Info=... rule parts to display message with corresponding severity

E.g. Name=Test rule name; 1000<ZIP<9999; Warning="Shipping might take longer due to strikes!"; Shipping=5

• Extend the library with functions error(...), notice(...), info(...) or extend warning(...) to warning(..., severity)
• Implement corresponding message functions in VM framework
• Implement corresponding message functions in WC framework
• Add those new "variable" names to the parser
• Store the messages in the rule when parsing
• Add a new function handleMessages and call it in checkConditions and getCosts before the handleNoShipping call