[Xfce-i18n] improve a exist translation

[Mike Massonnet]

Vincent Nguyen wrote:
> @Mike Thanks for your instruction!
> @Per Thanks for your information!
> I look at wiki, but i'm a newbie and it contains about confusion 
> infomartion:-)!
> So, i'm translating thunar right now and will attach file to send to 
> this group!

Ok, if there is something wrong with your first translation we will tell 
you. It shouldn't be too hard ;-)

Regards
Mike