cssshadowvalue: Add a cache for blurred Pango layouts

Drawing text with Pango is quite expensive, and drawing text and also
blurring it is *really* expensive. To prevent us from drawing a lot of
text and then blurring it a lot is *really* expensive.

We now cache the blurred pixels for the last layout and shadow we made,
which means we can repeatedly draw labels with a blurred text-shadow
extremely fast.

To detect whether the shadow is up-to-date, we track the serial of the
PangoLayout alongside the radius of the box shadow. We don't support
inset shadows nor spread on text-shadow, so we don't need to track
these.
gdk: Deprecate static gravities

... and remove all implementations. The API allows to not work "if the
server doesn't support it. So from now on, no server does!
gdk: Allow calling gdk_cairo_surface_create_from_pixbuf with scale 0

The documentation explicitly states that 0 is an allowed value for using
the same scale as the window. This 0 value is also explicitly checked
down in the call chain and handled.
Updated Korean translation
gdk: Fix gdk_cairo_create() without begin_paint()

We were translating the clip region twice in that case.

https://bugzilla.gnome.org/show_bug.cgi?id=737825
gdkwindow: Fix small typo
Fix monitors enumeration bug

Fix monitors enumeration bug. By default used MONITORINFOEXW (UTF-16 Build) with wrong structure size
tooltip: fix line wrapping

We enable line wrap on the internal GtkLabel, but nowadays this does
nothing unless we also set a max number of characters.

https://bugzilla.gnome.org/show_bug.cgi?id=737929
Add GtkTextViewClass to the docs

So that the existing information about draw_layer actually
ends up in the docs. While we are at it, document the other
vfuncs.

https://bugzilla.gnome.org/show_bug.cgi?id=737952
GtkStackSwitcher: Pick up the visible child from the stack

We forgot to synchronize the visible child when setting a
stack on the switcher. Oops.
GtkSidebar: Pick up the visible child from the stack

Same here: We need to synchronize the visible child with the
selected row when setting a stack on the sidebar. I've noticed
this problem in the sidebar example in gtk3-widget-factory.
GtkTextView: Add a monospace property

This is a convenient shortcut for a common case. It is implemented
by adding a .monospace style class to the text view, and letting
the theme decide about the monospace font to use.
Adwaita: Add .monospace style
Inspector: Use the new monospace support
Inspector: Use text attributes for monospace labels
gtk3-demo: Don't use deprecated API

Replace various override calls.
Adwaita: change spinbutton button color on backdrop

Contextually dim the spinbutton button color a little bit.
Add a style class for touch selection popovers
Make touch-selection popovers font-inert

Just like context menus, these should not inherit font
settings from the text view they are attached to.
printing: Properly initialize auth_info in gtkprintbackend.c

auth_info should be a NULL-terminated array as it is used in
e.g. g_strdupv invocations iterating over its elements until
a NULL element is encountered.

https://bugzilla.gnome.org/show_bug.cgi?id=737777