Finally make the new converter work. API-wise it is as good as the old one (can import everyting, the old one could),
but design-wise it might be much more powerfull. Basically it can handle/convert all content-types for which one can
create an Add- or EditForm? successfully. In other words: if you manage to write an edit form for some content type,
then you can also create an importer for that content-type. Still finetuning needed (for dates, bool data, etc.) but
the main things work.