Before modifying question object layout

Did already quite a few additions to bring the converter up do date.
Not working yet though, I think I need to change the question
object layout (although I don't even understand how the plugin could
work as it is at the moment).
Therefore a careful commit beforehand.
Converter now producing XML file with Moodle 2.5

Haven't looked at the output yet, but at least
no errors and warnings anymore.