GtkMenuButton: Submit to action

As an actionable (inherited from GtkButton), a GtkMenuButton
should not set its own sensitivity when it has an action-name
set, but just follow the enabled state of the associated
action.

https://bugzilla.gnome.org/show_bug.cgi?id=738083
Add a note about text view issues

Mention text view background problems and the draw_layer
vfunc in the release notes.
tests: Exit test when main window is closed
render: Optimize the no-borders case to exit early
shadows: Respect scaled factors for cached surface
GtkScrolledWindow: Allow scrolling without bars

Add a new policy, GTK_POLICY_EXTERNAL, which hides the scrollbar,
but does not force the scrolled windows size to be determined by
its child. This can be used to keep two scrolled windows in sync,
while sharing a single scrollbar.

https://bugzilla.gnome.org/show_bug.cgi?id=730730
Add an example for synchronized scrolling

This example uses GTK_POLICY_EXTERNAL to share a scrollbar among
multiple scrolled windows.
GtkScrolledWindow: Introduce a helper function

Instead of making assumptions about enum value ordering,
introduce a helper function to determine policy values
for which the scrollbar may be visible.
inspector: Add a way to disable the warning dialog
Update paper size names

Update list of standardized paper size names from
PWG Media Standardized Names 2.0 (MSN2) and from
CUPS' cups/pwg-media.c.

https://bugzilla.gnome.org/show_bug.cgi?id=725441
Create paper size from IPP media name

Add function gtk_paper_size_new_from_ipp() which looks for
given name in standard paper size names list and create appropriate
GtkPaperSize.

https://bugzilla.gnome.org/show_bug.cgi?id=725441
Remove dead code from CUPS backend

https://bugzilla.gnome.org/show_bug.cgi?id=725441
Get paper sizes from IPP query

Query printer via IPP for paper sizes if there is no
or empty PPD file.
Parse "media-supported" and "media-size-supported" attributes for list
of paper sizes. Parse "media-default" and "media-col-default" attributes
for default settings.

https://bugzilla.gnome.org/show_bug.cgi?id=725441
Add top/bottom style classes to scroll arrows
Updated Italian translation
Adwaita: style menu overflow button

See bug https://bugzilla.gnome.org/show_bug.cgi?id=738158
Adwaita: dim menu overflow button border color
gtkplacessidebar: Don't change location if clicked on eject button

Currently we change the current location if we click the eject button of
a mount.

Check whether the user actually clicked the eject button and don't
change location in that case.

https://bugzilla.gnome.org/show_bug.cgi?id=737983
gtkplacessidebar: Open $HOME after unmounting or ejecting

When a drive is ejected or a volume unmounted the current directory
doesn't change most of the times being empty or being a directory that
user shouldn't take care about, like /run/media

Seems more useful to change to $HOME directory in that case so the user
can see something useful and familiar just after unmounting.

https://bugzilla.gnome.org/show_bug.cgi?id=737983
wayland: write wl_data_offer data asynchronously

Currently writing wl_data_offer data into the fd is 1) synchronous, which
is noticeable when transferring large amounts of data, and 2) buggy, write()
error checking is done on the accumulator, breaking both the written data
accounting and error checking itself.

Fix both by making writes asynchonous through GOutputStream, the operation
is spun off and either finished, or cancelled if new data is stored in the
selection while the transfer is active.