[gtk] (34 commits) Non-fast-forward update to branch wip/baedert/stb-rect-pack

[Timm Bäder <baedert src gnome org>]

The branch 'wip/baedert/stb-rect-pack' 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:

  145a81f... glglyphcache: Use stb_rect_pack for better glyph packing
  f8629eb... gl renderer: Move texture atlas into its own file
  cc82e83... glimage: Only support uploading one region

Commits added to the branch:

  89d8ae0... stack: Fix a crash (*)
  acaa257... Updated Slovenian translation (*)
  cd37b87... overlay: Remove hack for scrolled windows (*)
  1f56f5c... selectionmodel: Change prototype of query_range() (*)
  0772258... simpleselection: Improve items-changed (*)
  2ba928e... window: Properly detect if size allocation is needed (*)
  e0ec5ca... container: Drop gtk_container_check_resize() (*)
  d3a2218... widget: Split up priv->allocation (*)
  d65a60e... widget: Move compuatation of what changed further up (*)
  2e5bc9f... gtk: Add the GtkRoot interface (*)
  aeda099... widget: Remove toplevel flag (*)
  4ca1f7e... widget: Add GtkWidgetClass:root and :unroot functions (*)
  ddf2a36... widget: Add a GtkWidget::root property and gtk_widget_get_r (*)
  2fbdd8b... root: Add GtkRoot:get_display vfunc (*)
  446713f... root: Add gtk_root_get_surface_transform() (*)
  694d7c3... root: Move the renderer to the root (*)
  86978d2... widget: Store the render node in the widget's coordinate sy (*)
  19ffb40... cssboxes: Introduce (*)
  285aba6... widget: Make width, height and transform be widget-relative (*)
  7ad0f7f... css: Mark some hot functions as G_GNUC_PURE (*)
  c44c44e... css: Pass boxes to the render functions (*)
  aa55222... singleselection: Make tests build without warnings (*)
  fb4f5e0... assistant: Add docs (*)
  d327d3f... assistant: Use a stack (*)
  e5e2bd3... Drop GtkAssistantPage::has-padding (*)
  74d6d81... Merge branch 'assistant-cleanup' into 'master' (*)
  bea1a02... Merge branch 'wip/otte/boxes' into 'master' (*)
  0739399... paned: Implement increased handle area using pick() (*)
  10e5856... widget: Save transform as matrix (*)
  ca2c05c... widget: Push a transform node if we need to (*)
  c9d9f8b... flowbox: Implement get_child_at_pos properly (*)
  c5c8fbb... glglyphcache: Use stb_rect_pack for better glyph packing
  a07341b... gl renderer: Move texture atlas into its own file
  eb506c2... glimage: Only support uploading one region

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