Updated Czech translation
Add support for rotating the wattermark.
Minor reformatting.
Merge branch 'rotate-watermarks'

* rotate-watermarks:
  Minor reformatting.
  Add support for rotating the wattermark.
Update French translation.
Merge pull request #589 from milankni/translation-cz

Updated Czech translation
Fix watermark rotation direction.
Add "screen_dpi_overwrite" to config

Setting this to a value > 0.0 will overwrite the screen's DPI setting to
scale the GUI accordingly without the need to mess with xrandr.
Fix computation of watermark center.
Fix typo, mipamps -> mipmaps.
Update copyright noctice.

copy/paste mistake when creating those files.
lua : modernize calling conventions to have more flexiblity
lua: allow sending lua commands via dbus

use org.darktable.service.Remote.Lua to send a lua string
lua: fix a typo in usermanual
dt_histogram_worker: fix memleak
Levels, exposure: better commit_params logic (in case of bad histogram)

Anything broken?
IOP Exposure: Deflicker: s/"thumbnail"/"pre-processed image"/
IOP Exposure: Deflicker: show mode switch only when dt_image_is_raw()
lua : return nil instead of NAN on latitude/longitude of images when not set
usermanual: several minor additions/corrections (plus xml source pretty-printing)