Draft prototype should use nt:unstructured for compounds from same namespace

The draft prototype (nt:unstructured itself) should use unstructured nodes for fields types from the same namespace. This allows the user to skip many "update all content" steps. (necessary when a change to a compound has been made)

SW: how would the user know when he can skip the update-all-content or not?
FvL: see https://issues.onehippo.com/browse/CMS7-2794