Create a XML Validator for QSTools

It should check if it is valid and validatable xml too.

i.e. have a DTD or XSD reference and actually validate.

Those are the issues we've bumped into a few times that yes, the example will run but when opened in an IDE (like eclipse) that is validating xml to find issues then add warning markers.

The grey area here is that the xml most likely work in the runtime, but that is because the runtime is trying to be forgiven, but the content is actually not valid according to the DTD or XSD.

I believe our interest is that our examples follows the DTD and XSD...and in case the DTD or XSD is the wrong part, we should get that fixed.