[gtk] (13 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:

  55138cd... Load pngs without gdk-pixbuf
  4fb7b27... Save pngs without gdk-pixbuf
  cd26a6d... Add tests for the png loader
  61ca6b1... Add code to load and save tiff files
  f633ffa... Load tiffs without gdk-pixbuf
  5ccf01f... Add tests for the tiff loader
  6f7219b... Add gdk_texture_save_to_tiff
  8c770b3... Use our png loader for content (de)serialization
  39db15a... Use our tiff loader for content (de)serialization
  ef803bd... Add contentserializer tests for textures
  ee0a51f... Add code to load jpegs
  8613845... Load jpegs without gdk-pixbuf
  5a1e13b... Add tests for the jpeg loader

Commits added to the branch:

  e94910e... Load pngs without gdk-pixbuf
  c415e10... Save pngs without gdk-pixbuf
  e2195e1... Add tests for the png loader
  af5510d... Add code to load and save tiff files
  c779b6c... Load tiffs without gdk-pixbuf
  f48a4fc... Add tests for the tiff loader
  0f7edd8... Add gdk_texture_save_to_tiff
  01b0f47... Use our png loader for content (de)serialization
  c558425... Use our tiff loader for content (de)serialization
  aa1ab78... Add contentserializer tests for textures
  13828ba... Add code to load jpegs
  6ab3501... Load jpegs without gdk-pixbuf
  09c5730... Add tests for the jpeg loader