Add Uzbek@cyrillic translation
layout: Reset the OSK to the primary monitor when monitors change

When monitors change, the previous index might not mean the same
physical monitor anymore, in fact, it might become invalid. In the
latter case, we'll actually get a JS error when accessing
this.keyboardMonitor in _updateKeyboardBox() . To avoid this, let's
just always reset the OSK to the primary monitor.

https://bugzilla.gnome.org/show_bug.cgi?id=738536
Fix handling of SystemBackground

Since the background rework, SystemBackground is no longer a transparent
actor that you have to stack on top of a solid background, it is an
opaque actor. Fix the color of the background actor, and remove places
where we were setting the background color underneath the system background
and expecting blending - in particular, we can always set no_clear_hint
on the stage.

https://bugzilla.gnome.org/show_bug.cgi?id=738652
Use LC_TIME locale for strftime format string translations

We commonly mark strftime format strings for translation to account
for date/time representations without an existing strftime shortcut
("Yesterday %H%p"). As those translations are looked up according to
the locale defined by LC_MESSAGES, while the conversion characters
themselves are resolved according to LC_TIME, the result can be
rather odd when mixing locales ("Den 27. January"). The correct
solution would be to install translations for format strings in
the LC_TIME catalogue and look them up with dcgettext(), but we
don't have the infrastructure to do that easily. Work around this
by adding a helper method that looks up a string in LC_MESSAGES
using the locale defined by LC_TIME and use that to translate
format strings, which has the same result.

https://bugzilla.gnome.org/show_bug.cgi?id=738640
theme: rewrite to be structured

- using SASS
- trying to reuse as much of the gtk adwaita as possible
theme: use Adwaita dark style for popup menus

- cannot sue box-shadow sadly.
theme: update some svg assets to adwaita 3.14 counterparts

- switches
- checkboxes
theme: fine tune scrollbars
theme: modal dialogs and tweaked entries
theme: top bar styling.
theme: overview search bar styling
theme: checkboxes
theme: top bar appmenu etc.
theme: volume/mic slider
theme: switches
theme: forgot old overrides of the panel styling
theme: top bar active is underlined.

- glow feels foreign, will be phased out
theme: remove unused assets
theme: overview styling

- still some quirks
- boy is this unstructured mess a pain to clean up :(
theme: workspace pager in overview