MonitorManager: emit a DBus signal when we change the display configuration

Using out-of-band notifications from the wayland protocol or from
X is racy, in that the client could ask for the new resources before
we have them.
Instead, with a signal, we are sure that when the client asks for
it, it will get the right values.

https://bugzilla.gnome.org/show_bug.cgi?id=706382
MetaPlugin: simplify the modal API

Remove grab window and cursor from the API, and just grab always
on the stage window with no cursor.
This is mainly to remove the X11 usage in the public API, in preparation
for implementing this in wayland.

https://bugzilla.gnome.org/show_bug.cgi?id=705917
ui: Disable scaling support in Gtk+

We can't really support the Gtk+ automatic scaling, as to much
code relies on the GdkWindow and XWindow sizes, etc to match.
In order to keep working we just disable the scaling, meaning
we will pick up the larger fonts, but nothing else. Its not
ideal but it works for now.

https://bugzilla.gnome.org/show_bug.cgi?id=706388
Require Gtk+ 3.9.11

This is needed for the gdk_x11_display_set_window_scale() call.
Updated Spanish translation
Update .gitignore
Updated Brazilian Portuguese translation
Updated Hebrew translation.
screen: Add _GTK_FRAME_EXTENTS to _NET_SUPPORTED
texture-tower: Remove CPU codepath for mipmap generation

The CPU codepath for mipmapping is unusably slow, and we expect modern
graphics cards with modern TFP/FBO support.
tower: make sure not to blend when updating tower

Each level in the tower is initialized by binding the texture for that
level to an offscreen framebuffer and rendering the previous level as a
textured rectangle. The problem was that we were blending the previous
level with undefined data so argb32 windows with transparencies would
result in artefacts. This makes sure to disable blending when drawing
the textured rectangle.
Updated slovak translation
window: Fix a compiler warning
tower: Fix erroneous return value

The function's return value is void, not gboolean.
Bump version to 3.9.90

Update NEWS.
Updated Polish translation
configure: Require Cogl 1.15.6

Needed for cogl_offscreen_new_with_texture
Update French translation
Drop man pages for removed utilities

Commit 8c1c77482db263a7dcc04051a9694f30a852b702 removed mutter-message,
mutter-theme-viewer, and mutter-theme-viewer; this drops their man pages
as well.

https://bugzilla.gnome.org/show_bug.cgi?id=706579
Updated Norwegian bokmål translation