Fix histogram double-click (initially reported by Roumano in darktable-devel ML)
colorin: notify user if color matrix is missing
Updated Dutch translation
Merge pull request #553 from MRIG/master

Updated Dutch translation
Updated Dutch translation
Merge pull request #554 from MRIG/master

Updated Dutch translation
Fix #9948: Don't optimize isnan() away

I wonder why they broke this and what will be next ...
First batch of high DPI fixes

Soem small things like the triangles in our custom dr widgets are still
missing, but the big issues should be solved now.
I only tested these thigns by setting the screen DPI using xrandr, I am
not 100% sure if that is a perfect simulation.
People using a high DPI screen should still set the panel_width in the
config to something bigger.
Fix libpng-1.4 build
fix several translating errors
fix base curve mismatching
update chinese translation
Merge pull request #555 from cherrot/i18n_zh_CN

I18N: Update Chinese translations. Fix several translating errors
High DPI: More fixes, this time cairo stuff

TODO:
 - color picker
 - masks
 - anything else?
Italian translation updated
Update French translation.
Merge pull request #556 from bartokk/master

Italian translation updated
Lens IOP: add autodetection, based on fact "did user or did not changed anything in GUI from autodetected values"
Merge pull request #548 from LebedevRI/lens-autodetection

Lens IOP: add autodetection