PROV-985 Added dontUseCDATA option for XML exports

This allows you to explicitly turn off all escaping and
wrapping-in-CDATA efforts the exporter takes. The field content is
entered as-is, even if it breaks the XML.
PROV-985 Two steps back, one step forward

It seems to be impossible to insert arbitrary field content, in
particular broken HTML/XML, into existing DOM trees without CDATA
sections. This is a good thing! But: As a hack for the problem at hand,
we now added an option that explicitly strips the CDATA tags before
exporting. Doing this is not recommended and the option will probably
be undocumented indefinitely. It just doesn’t make sense in normal
scenarios.