[gtk] (14 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:

  ff3597e... Add code to load and save pngs
  06a9917... Load pngs without gdk-pixbuf
  4d04681... Save pngs without gdk-pixbuf
  f6ebbec... Add tests for the png loader
  9f6d7f4... Add code to load and save tiff files
  dcdad73... Load tiffs without gdk-pixbuf
  1520a04... Add tests for the tiff loader
  3ad79f5... Add gdk_texture_save_to_tiff
  648719b... Use our png loader for content (de)serialization
  70ca70b... Use our tiff loader for content (de)serialization
  e2cef3d... Add contentserializer tests for textures
  0ba9cd0... Add code to load jpegs
  73966cf... Load jpegs without gdk-pixbuf
  fa62c6a... Add tests for the jpeg loader

Commits added to the branch:

  6664c94... Add code to load and save pngs
  1d664e7... Load pngs without gdk-pixbuf
  b9c93ee... Save pngs without gdk-pixbuf
  f4c462f... Add tests for the png loader
  43f4b9e... Add code to load and save tiff files
  a39b374... Load tiffs without gdk-pixbuf
  823996a... Add tests for the tiff loader
  76839d0... Add gdk_texture_save_to_tiff
  1cbd0d4... Use our png loader for content (de)serialization
  59475d1... Use our tiff loader for content (de)serialization
  9169ff4... Add contentserializer tests for textures
  7a9a3be... Add code to load jpegs
  46cd137... Load jpegs without gdk-pixbuf
  20273e8... Add tests for the jpeg loader