Merge branch 'prep-release-3.0.11'

* prep-release-3.0.11: (279 commits)
  [prep-release-3.0.11] Bumping version number for 3.0.11 final.
  [prep-release-3.0.11] Update Changelog for 3.0.11-RC2 release.
  [prep-release-3.0.11] Bumping version number for 3.0.11-RC2.
  [ticket/10965] Profile data is only grabbed when show_novalue is enabled
  [ticket/10965] Make sure all profile fields are always grabbed on viewtopic
  [ticket/10965] Database update was referring to 3.0.5 instead of 3.0.11-RC1
  [ticket/10965] Introduce a new profile field option to display no value
  [ticket/10667] Fix tests under MySQL 5.5 strict mode (once again)
  [ticket/10950] Fix grammar in comments
  [ticket/10950] Delete PMs for users that have not yet read the pm
  [ticket/10950] Fix unit tests to fit the new pm deleting behaviour
  [ticket/10950] Update undelivered pm counts in batches not 1 by 1 for each user
  [ticket/10950] Remove deleted entries in tests instead of commenting them out
  [ticket/10950] Use database count() and group by instead of doing that in php
  [ticket/10978] Fix typo in prosilver ucp_groups_membership.html
  [ticket/10950] Check $delete_ids to be not empty
  [ticket/10950] Recreated the behaviour of phpbb_delete_user_pms()
  [ticket/10950] Fix unit tests to reflect desired behaviour
  [ticket/10441] Make CDB linking more consistent
  [ticket/10937] Update documentation to say which comment styles are removed.
  ...
Merge remote-tracking branch 'upstream/master' into develop