Distinguish between open and closed vocabularies
We seem to need a distinction between the vocabularies, if they allow for new concepts to be added/suggested, or if they are considered closed. Closed meaning mostly, we reuse an existing vocabulary from external authority. In this case we don't want to edit it (adding new concepts etc.) and the only change is, if there is new version from the authority.
This should be probably an additional attribute of a vocabulary, i.e. slight change to data model. For closed vocabularies it shouldn't be allowed to create new candidate concepts.
(notify: @lbarbot, @klaus.illmayer, @mkozak, @stefan.probst )