Correct bug with LANG + installation

I've corrected a little bug : the LANG variable wasn't evaluated, and I renamed LANG into LANGUAGE because it there were a conflict with the system variable LANG.

**You MUST MODIFY some scripts by replacing LANG with LANGUAGE (I think only gmaps uses it)**

I modify too the setup file because the "-c root" option doesn't works in KDE (can you check that It still works in Gnome/Unity ?), now KDE can also use this script even if gksu isn't installed.

**This script must NOT be executed as root because if it does all files are created with root as belonger and users cannot modify it**