usermanual: proofreading new stuff thanks to David Vincent-Jones
Merge branch 'master' of https://github.com/darktable-org/darktable
Proof reading of my traducted part of the usermanual of darktable 1.5 after a 'make update-usermanual-fr'
	modified:   ../doc/usermanual/po/darktable-usermanual.pot
	modified:   ../doc/usermanual/po/fr.po