[gtk] (16 commits) ...Merge branch 'wip/otte/float-textures' into 'master'

[Benjamin Otte <otte src gnome org>]

Summary of changes:

  0ee3b1c... texture: Remove unused argument from vfunc (*)
  51d0d13... gltexture: release() to a texture, not a cairo_surface (*)
  9c8e464... texture: Add GdkMemoryConversion private enum (*)
  4f17f3a... texture: Add gdk_texture_download_texture() (*)
  74ce69a... gltexture: Make release() use download_texture() (*)
  c349ed9... gltexture: Implement download() via glGetTexImage() (*)
  cbe6d0d... gdk: Deprecate gdk_cairo_draw_from_gl() (*)
  5327548... texture: Add gdk_texture_download_float() (*)
  1759d27... memorytexture: Add support for HDR formats (*)
  719eafa... gl: Implement uploading and downloading HDR formats (*)
  c9d748f... testsuite: Overhaul memorytexture test (*)
  00439f9... testsuite: Rework memorytexture test some more (*)
  bcc17b3... testsuite: Add tests uploading the memorytextures (*)
  9179ebb... testsuite: Add memory test support for OpenGL up/downloads (*)
  416763b... testsuite: Add tests for gdk_texture_download_float() (*)
  6bbec87... Merge branch 'wip/otte/float-textures' into 'master'

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