Enable warnings at the Parser level

[hanjoosten]

We still have an old version of the VIEW statement in the current syntax. In order to get rid of this in the future, it would be nice to be able to warn people if they still use it. This requires the ability to add warnings to the Parser State. The Parser State currently only contains the current position of the parser. If that would be extended with a list of warnings, that would suffice to implement warnings at the parser level. :)