remote-display: if llvmpipe was detected, disable animations

If _GNOME_IS_SOFTWARE_RENDERING X Atom is detected on root window,
disable animations.

https://bugzilla.gnome.org/show_bug.cgi?id=704402
datetime: Display notifications on timezone changes

Also, bump glib dependency to 2.37.7 for new %z format modifiers.

https://bugzilla.gnome.org/show_bug.cgi?id=707191
datetime: Use reverse geocoding for country detection

Previously, we would get the current coordinates from geolocation and
then try to match them to the offline timezone database. This commit
adds one more step to make the matching more accurate: reverse geocoding
in order to narrow down the location to a specific country.

In an ideal world, we'd be able to get the timezone directly from
reverse geocoding. Nominatim, the service that geocode-glib uses,
however doesn't offer timezone information yet:
https://trac.openstreetmap.org/ticket/4200

Instead, we use geocode-glib to find out the country, and then do
timezone mapping ourselves.

https://bugzilla.gnome.org/show_bug.cgi?id=707200
datetime: Use geocode-glib for calculating distances

Now that we're linking with geocode-glib anyway, we can drop copy-paste
distance calculation code and use geocode_location_get_distance_from()
from geocode-glib instead.

https://bugzilla.gnome.org/show_bug.cgi?id=707200
datetime: Use libgweather's timezone info

In addition to the Olson timezone DB, we're now merging in the timezone
location info from libgweather as well. This should make the timezone
autodiscovery more accurate and is hopefully good enough to turn it on
by default.

https://bugzilla.gnome.org/show_bug.cgi?id=707241
build: Bump required gsettings-desktop-schemas version to 3.9.91

Needed for the new org.gnome.desktop.datetime schema.
Updated POTFILES.in