Allow editing events even with token-protected tags

[wellemut]

Problem

Events, that use a protected token for controlled maps, can not be edited by others. Error message:

http_status	403
message	"The tag is owned by an organization"

Solution

Make it the same way as with places:

• Allow all editing
• but add the entry to the clearance-center list

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Merge the events into the places DB, so that we have revisions, org-tags and custom-links also for events #316