csd: Improve the window title

Manually create the label, so that we can set its margins.
csd: Use a dedicated style class for window buttons

This allows themes to differentiate between regular buttons
in a title bar, and window buttons.
csd: use the correct icon name for close button

The icon is called window-close-symbolic.
csd: Improve window button handling

Group the buttons on each side in a box, and give them different
style classes, so themes can differentiate (this is partially a
workaround for limitations in our css selectors). The boxes also
let us add a margin below the buttons, without affecting the
allocation of the buttons themselves.
GdkDeviceManagerXI2: chain up in constructed

Dispose does chain up, and the parent class' dispose expects
that the object has been fully constructed.
GdkVisualX11: Add a dispose implementation

We need to be able to drop X resources before finalization.
GdkScreenX11: Dispose visuals

If we let them hold onto their X resources until finalize,
it is too late.
Add a testcase for closing display before exit

It works right now, lets keep it that way.
typo fix
Add a --direction option to gtk-reftest

gtk_test_init() hardcodes the locale to "C", so the --direction
option is useful to check reftests in rtl.
reftests: Add a reftest for the expand change in GtkBox

The change was introduced in 80513aa2c7ed4aecc235723ea6c6f044cf98ba1d

See that commit for details.
Avoid integer overflow

Use g_malloc_n in gdk_cairo_set_source_pixbuf when allocating
a large block of memory, to avoid integer overflow.

Pointed out by Bert Massop in
https://bugzilla.gnome.org/show_bug.cgi?id=703220
GtkHeaderBar: documentation improvements

Add some more information about title allocation.
GtkSearchBar: formatting trivia
Add missing GtkSearchEntry API to the docs
Add GtkListBox to the widget gallery
textiter: better document "tag" functions

https://bugzilla.gnome.org/show_bug.cgi?id=703313