Merge branch 'master', remote-tracking branch 'remotes/upstream/master'

Merge branch 'master', remote-tracking branch 'remotes/upstream/master'

* remotes/upstream/master:
  apply max-width to images in posts, duepuntozero
  theming for default group selector
  catch more places to apply default group
  make it difficult to setup a private forum with no privacy
  more private forums, default privacy group for new contacts
  tell browser not to cache permission denied (private) photos so that after authenticating we don't have to fight the browser - plus more prvgroup work

* master: