[gtk] (4 commits) Non-fast-forward update to branch clipboard-test

[Matthias Clasen <matthiasc src gnome org>]

The branch 'clipboard-test' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  9770315... Add a clipboard test client
  13d3ecb... contentserializer: Don't write to a closed stream

Commits added to the branch:

  f34e3c5... clipboard: Make sure G_TYPE_STRING is nul-terminated (*)
  1be8994... clipboard: Fix reading of files (*)
  1a12ea6... Merge branch 'wip/otte/for-master' into 'master' (*)
  f71d271... Add more clipboard tests

(*) This commit already existed in another branch; no separate mail sent