OSX HiDPI: fix most places, central DR view is still broken
OSX HiDPI: revert changes to map.c from last commit

since osmgpsmap will draw pixelated map anyway
OSX HiDPI: fix logo in bg of zonesystem
OSX HiDPI: fix slideshow view
OSX HiDPI: return correct mipmap level for HiDPI screens
OSX HiDPI: fix central DR view
OSX HiDPI: update package building instructions
OSX HiDPI: add config option and disable for old cairo
bauhaus: make version for the visually impaired compile again
Clang-format: disable formatting for src/external/
wb_presets: Panasonic GF5

samples kindly provided by Pavel Nakonechny
wb_presets: Panasonic GH2 cosmetic corrections
Make shooting in tether mode work

When using the shutter button on the camera dt should react by
downloading the image and importing it. However, there was no listener
by default which did that, so the images ended up under /tmp/ and didn't
get imported. No idea since when that was the case. I hope that it works
now.
Caveat: This has the slight chance of a race condition when having the
import from camera-dialog open while in tethering mode, since the
previews grabbed from the camera could end up bein treated as images. At
least that's my theory. In practice it should not be possible to have
the dialog open while in tethering mode so I don't care too much for
now.
wb_presets: update x100s (stolen from ufraw)
adobe_coeff: add some basic context info
[l10n] Update Ukrainian translation
Preliminary update of the Russian translation (90% done, more to follow)
Updated Russian translation (97% done, good to go)
Merge pull request #778 from parafin/macosx

Retina support
Switch to GTK3 in cmake