[gtk] (12 commits) Non-fast-forward update to branch image-loading

[Matthias Clasen <matthiasc src gnome org>]

The branch 'image-loading' 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:

  1e6df99... Save pngs without gdk-pixbuf
  27a4ef1... Add tests for the png loader
  59f6855... Add code to load and save tiff files
  458eb88... Load tiffs without gdk-pixbuf
  a60d8db... Add tests for the tiff loader
  d2b0ac1... Add gdk_texture_save_to_tiff
  18fd6a3... Use our png loader for content (de)serialization
  3d04632... Use our tiff loader for content (de)serialization
  5effee3... Add contentserializer tests for textures
  f71757d... Add code to load jpegs
  913e825... Load jpegs without gdk-pixbuf
  2254071... Add tests for the jpeg loader

Commits added to the branch:

  ae91d71... Save pngs without gdk-pixbuf
  6ccc978... Add tests for the png loader
  fcce2d9... Add code to load and save tiff files
  2499ef2... Load tiffs without gdk-pixbuf
  d199d97... Add tests for the tiff loader
  49b9095... Add gdk_texture_save_to_tiff
  2aa01b2... Use our png loader for content (de)serialization
  54d173e... Use our tiff loader for content (de)serialization
  1e7f473... Add contentserializer tests for textures
  6eff7fb... Add code to load jpegs
  1b25063... Load jpegs without gdk-pixbuf
  b1cb8ea... Add tests for the jpeg loader