fix for #10012

the sql statement in image.c:782 was just terribly wrong. while trying to handle
grouped images it would overwrite existing xmp files in adverse conditions.
imageop: tune up X-Trans bilinear downsample

don't offset up/left compared to VNG/Markesteijn
use floor of sample size for more sharpness
import: avoid intermingled use of sqlite stmt within dt_image_import()
Italian translation updated
Merge pull request #640 from bartokk/master

Italian translation updated
Update French translation.
lua : add a few cases of cross-reference within the documentation
lua : more severe #ifdef around lua command line options

not sure why this breaks some compilers, but apparently it does, so fix it
Merge pull request #636 from upegelow/xmp_overwrite_fix

fix for #10012
gtkrc: neutralize remaining colors
adobe_coeff: NIKON D810 support
rawspeed: experimental NIKON D810 support
Also rename isldr to format in legacy_presets

This was an oversight in 1492e024f4952e4fc7e0fa952b7fe35c2e20f755
fix handling of groups on image copy
Rawdenoise: disable piece if !(d->threshold > 0.0f)
Exposure: disable piece if no-op
#10029: fix lens detection for Sony ILCE bodies
Merge branch 'master' of https://github.com/darktable-org/darktable
[l10n] Swedish update
New Nikon D800 basecure computed with dt-curve-tool.

This new basecurve looks far better in the dark tones and closer to
the corresponding jpeg used during the process.