about dialog: differentiate GPL "or later" versions

https://bugzilla.gnome.org/show_bug.cgi?id=720410
about dialog: add docs for new GtkLicense values
gdkwindow: Handle references in "update_windows" list correctly

Since update_windows list is a static variable in GdkWindow.c which
contains pointers to windows which needs to be updated, it can happen
that it contains a pointer to a window even after quit from a gtk_main().
If another gtk_main() is called in the same process it tries to process
windows in the list which leads to a crash.
Correct reference count handling of added windows prevents such applications
from crash.

https://bugzilla.gnome.org/show_bug.cgi?id=711552
Updated Hebrew translation

Signed-off-by: Yosef Or Boczko <yoseforb@gmail.com>
Fix up default csd titlebars

We were forgetting to show close buttons, and the spacing
was wrong, too.
bloatpad: test inhibit

Add an inhibit for logout when there is context in the text buffer.
Refactor GtkApplication

gtkapplication.c has turned into a bit of an #ifdef mess over time, and
many of the current checks are incorrect.  As an example, if you build
Gtk for wayland, and exclude the X11 backend, much of the functionality
required by wayland (such as exporting menu models) will be disabled.

Solve that by introducing a backend mechanism to GtkApplication (named
GtkApplicationImpl) similar to the one in GApplication.  Add backends
for Wayland, X11 and Quartz, with X11 and Wayland sharing a common
'DBus' superclass.

                             GtkApplicationImpl
                                      |
                       /--------------+-------------------\
                       |                                  |
            GtkApplicationImplDBus              GtkApplicationImplQuartz
                       |
           /-----------+-----------------\
           |                             |
  GtkApplicationImplX11      GtkApplicationImplWayland

GtkApplicationImpl itself is essentially a bunch of vfuncs that serve as
hooks for various things that the platform-specific backends may be
interested in doing (startup, shutdown, managing windows, inhibit, etc.)

With this change, all platform specific code has been removed from
gtkapplication.c and gtkapplicationwindow.c (both of which are now free
of #ifdefs, except for a UNIX-specific use of GDesktopAppInfo in
gtkapplicationwindow.c).

Additionally, because of the movement of the property-setting code out
of GtkApplicationWindow, the _GTK_APPLICATION_ID properties (and
friends) will be set on non-GtkApplicationWindows, such as dialogs.

https://bugzilla.gnome.org/show_bug.cgi?id=720550
Updated POTFILES.in
gtkapplication: fix inhibit

The big refactor contained a small mistake that broke inhibiting.  Fix it.
Fix a11y testsuite for about dialog changes
testtitlebar: Add custom content

This will help in tracking down size allocation issues
in GtkHeaderBar.
GtkHeaderBar: Fix allocation of start and end boxes

We were giving these boxes too much width, consuming what
was supposed to be the spacing between the boxes and the
other content of the header bar.
Fix accessibility tests for real

The character count had to be updated as well.
[l10n] Updated Italian translation.
Fix make dist
Fix extraction of some translatable strings

The reason why some of the strings in gtkprintunixdialog.ui
were missing is that we did not extract translatable string
from <item> elements. Fix that.
3.11.3
Bump version
GtkStyleContext: Invalidate contexts with a path

Fixes a tiny typo in commit f51c9d4154ba1ce4f20f7c4b7f705fe2756cb8ab
which manifested itself in GtkSpinButton's panels being drawn with an
incorrect, not updated state.

This patch took me more hours than you might think! :P

https://bugzilla.gnome.org/show_bug.cgi?id=709491
GtkAppChooserWidget: Monitor installed applications

This uses the new GAppInfoMonitor object in GIO, which provides
change notification when the set of installed applications changes.