Add config option to enable FormBuilder feature
add first prototype of rdfauthor-template
needs a template resource to work correctly
Add query for classes bound to a template

If RDFauthor template mode is active we check if the selected class is bound to a
template resource and load exactly the properties specified there. If we do not find
a suitable template we fall back to normal behaviour of RDFauthor.
Fix conflict when creating instance while editing

Ad hoc fix that prevents a user from creating a new resource via the
class module context menu when there is already a RDFAuthor widget open.
Allowing both at the same time will lead to conflicts that could maybe be
resolved later on.
Forward RDFauthor