[gtk] (5 commits) Non-fast-forward update to branch heif-demo

[Matthias Clasen <matthiasc src gnome org>]

The branch 'heif-demo' 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:

  6a995d7... Add a quick-and-dirty heif loading test

Commits added to the branch:

  0beab5f... colorprofile: fix up the docs a bit (*)
  da75563... gltexture: Improve the docs a bit (*)
  3fc8ac8... gsk: Fix a formatting mishap (*)
  4115865... Add a quick-and-dirty heif loading test
  2f03082... widget-factory: Add an hdr image example

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