[gtk] (28 commits) Non-fast-forward update to branch wip/chergert/opbuffer

[Christian Hergert <chergert src gnome org>]

The branch 'wip/chergert/opbuffer' 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:

  675cbcc... prototype OpBuffer helper for building op buffer
  f6a36fe... gl: fix linear gradients
  0acb26a... Drop OP_CHANGE_VAO
  843537c... gl: Drop buffer_size
  0f304e5... Merge branch 'wip/chergert/opbuffer'
  8dd6459... gl: avoid calculating vertex_data until necessary
  96c9b2e... Fix load_vertex_data

Commits added to the branch:

  977ac2b... gl: Do less work on glyph caching (*)
  123cbd4... gl: Make icon cache work like glyph cache (*)
  d3ad178... Merge branch 'glyphcache-fiddling' into 'master' (*)
  f9e100c... menu: Remove menu_queue_resize (*)
  93122ac... menu: Remove unused members (*)
  d570121... menu: Align function parameters (*)
  4c4bca0... menuitem: Remove unused members (*)
  7344723... colorscale: Remove some duplicated code (*)
  989307e... stackswitcher: Inherit from GtkWidget (*)
  b8f62d1... Update stackswitcher CSS (*)
  60d63bb... gl: Improve debug spew for caches (*)
  88649b6... gl: Interleave cache aging (*)
  e9ba7ed... gl: Increate the cache check frequency (*)
  e46a7ca... shadow cache: Remove outdated comments (*)
  7bff3ab... glyph cache: Fix handling of big glyphs (*)
  acb7f43... notebook: Avoid a crash (*)
  a00d12c... prototype OpBuffer helper for building op buffer (*)
  571068a... Drop OP_CHANGE_VAO (*)
  58d57e1... gl: Drop buffer_size (*)
  97f3371... gl: avoid calculating vertex_data until necessary (*)
  b53fa48... Fix load_vertex_data (*)
  49748c9... Some more vertex data reshuffling (*)
  c5af463... Cache glyph textures in render nodes (*)
  e34d1b8... gl: Slightly rework the icon cache api (*)
  dd5ee87... gl: Speed up icon cache lookups (*)
  7197743... pixbuf utils: Preserve format information (*)
  be13a23... icon theme: Avoid mime sniffing (*)
  0895f02... icon theme: Avoid a string copy (*)

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