Add keywords, as recommended here:

 http://standards.freedesktop.org/desktop-entry-spec/latest/ar01s05.html,
 http://bugs.debian.org/693918, and
 https://wiki.gnome.org/Initiatives/GnomeGoals/DesktopFileKeywords
Keywords value MUST end with a semicolon
Don't switch group if module activated via hotkey is already visible
interpolation: OpenCL implementation of interpolation_resample

implementation with naive 1:1 copy of CPU code. as to be expected this is
slow as hell combined with a huge workload on the gpu
Merge branch 'master' into interpolation
Merge branch 'master' into interpolation
opencl, interpolation: a bit less naive implementation
opencl, interpolation: make better use of local memory

speed wise this should now be ahead of the CPU code
opencl, interpolation: small fix and some added comments
Bug 9807: Correct Olympus Focus Distance

Originally the Focus Distance seems to be stored in a Rational (Fractional) format.

There seems to be some confusion about where the stored value is in centimeters versus millimeters.

This confusion seems to stem from the fact that some implementations seem to ignore the denominator of 10,
using the numerator directly (and incorrectly).

Exiv2's toFloat function properly divides the numerator by the denominator when outputting a Float (as centimeters).

So we need to divide by 100 to get meters.
(cherry picked from commit e32e81be92e8cfba9b728b272828da2173e8b3fc)
Olympus seems to have strange focus distances

This hopefully fixes #9807 for real now.
Rewrite of tiff file reader.
Clarified codepaths based on tiff format to simplify future work of
implementation of seperate contif format.

This commit also includes a few crushed bugs and fixes #9821
more protection against OOM in masks
make it possible to force-disable OpenEXR from the command line

inspired by PR 377 by LebedevRI
allow to force-disable webp from the command line

inspired by PR 377 by LebdevRI
Merge pull request #437 from levitte/gnome-desktop-add-keywords

Add keywords to darktable.desktop
.desktop: initial dutch keywords
imageio: lower default jpeg quality to 95

because 7c520cb3dcaba2be619e393c73c22f30f819c90e alone
didn't quite do the job :)
opencl, interpolation: catch cases where the GPU code cannot process efficiently: fall back to CPU
Merge pull request #468 from upegelow/interpolation

OpenCL implementation of pixel interpolator