Calculate only once.
Fix referrers with slashes.

No idea why this was necessary nine years ago. It doesn't seem to be required
anymore, but instead breaks referrers in rendered text. Could be some change in
Text_Wiki or Horde_Url.
Fix converting annotated wiki links.
Skip this part if there are no references.
[jan] Fix updating annotated links when renaming pages.
Check permission when editing notes.
[jan] SECURITY: Fix permission check when editing notes (found by Christopher Neuhaus <cne@ruhrverband.de>).
Prepare release.