Geo based wallpaper

[lkocman]

We have quite some ideas in #155 In most cases I find chameleon adding a "childish" factor to the wallpaper. And another problem is that we'd have way too many wallpapers. If we always show just one based on where you're currently based, then we can keep the total amount of wallpapers in background selection down to 5-6. Which is where I'd like to be.

However, I'd very much like to take the existing work, keep distro-specific elements (constellation or clouds-shaped logos, etc) turn it into a continent/geo-specific work. I very much like the factor of connecting communities to projects based on location.

This would probably require some startup script that locally figures out the closest match to one of our wallpapers and makes a geo symlink or similar.

Wallpapers should not be on live CDs (therefore part of the basic branding/wallpaper package) but should be installed on regular full install (e.g. by using recommendations).

One thing ... I'd avoid doing Day/night variants for each Location, I'd pick whatever works best and would focus on making them slightly different. e.g. don't use logos as star constellations, or cloud logos on each, find more interesting ways, etc, to make them more unique.

[lkocman]

I suggest to close our #155 in favor of this one, pick few agreed Geos and focus on one wallpaper per identified geo. We can add geo over times, accept new contributions with new locations over the time. I think this could be beginning of something very cool. I think this should probably be a separate package though.

[lkocman]

https://github.com/lkocman/geo-wallpapers experiment that does not work with symlinks but uses gsettings for a plain demonstration of TZ-offset based closest-match :-)