Fix 4157: Display error message when using "Change Login Information / Copy User" dialog to update password

Hi,

I did a bugfix by sending a message error if the user doesn't change username or hostname.
You'll find the modification in the last file of the comparison. (Other are the .po files.)

I added a new translation and also generated .po files and did the French translation.
I ran the generate-mo script, but nothing happened... Maybe something is missing...