[gtk] (9 commits) Non-fast-forward update to branch wip/matthiasc/gsk-hdr

[Matthias Clasen <matthiasc src gnome org>]

The branch 'wip/matthiasc/gsk-hdr' 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:

  95b01af... texture: Add hdr api
  720bd4a... gsk: Add hdr rendernode api
  f43af89... ngl: Allow specifying texture formats
  ca5565e... ngl: Determine intermediate formats
  d757905... ngl: Update hdr for each frame
  9083122... Revise the format check
  6ca5ea6... Clarify the docs
  ef778c8... ngl: Simplify framebuffer format handling

Commits added to the branch:

  cc6cc19... memorytexture: Split out GdkMemoryFormat handling (*)
  d087b8b... gl: Move memory <=> GL format mapping (*)
  45274bf... memoryformat: Add gdk_memory_format_prefers_high_depth() (*)
  83eb084... gdk: hdr => high depth (*)
  8ac51ed... texture: Add highdepth api
  2af3900... gsk: Add high depth rendernode api
  d612dc7... ngl: Allow specifying texture formats
  da54b69... ngl: Determine intermediate formats
  c109de6... ngl: Update framebuffer format for each frame

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