[gtk] (8 commits) Non-fast-forward update to branch gamma-shenanigans

[Matthias Clasen <matthiasc src gnome org>]

The branch 'gamma-shenanigans' 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:

  29b9eb8... Support loading and saving float textures
  8d6353c... Redo the conversion setup for memory formats
  ff55331... Allow conversion to hdr formats
  9f055fe... Add gdk_texture_download_float
  0ab4f76... Add async png load/save code
  6798fcd... Use our png loader for content (de)serialization

Commits added to the branch:

  f86bc6a... Support loading and saving float textures
  2193c15... Redo the conversion setup for memory formats
  e12de89... Allow conversion to hdr formats
  ef2d528... Add gdk_texture_download_float
  980cc99... Add async png load/save code
  ef2dba4... Use our png loader for content (de)serialization
  dab5669... Add async tiff load/save code
  5d175a4... Use our tiff loader for content (de)serialization