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.
Merge branch 'master' of https://github.com/darktable-org/darktable
Translating and proof reading of darktable's usermanual till section 3.2.7 (not included)
	modified:   doc/usermanual/po/darktable-usermanual.pot
	modified:   doc/usermanual/po/fr.po