[feladat @ 91] Fixing some language issues. Translations not working due to wrong file names, see r89 as well. Fixing two broken references in menu and list_zones.php.

[feladat @ 90] Fixing #1 ("password of user is shown in plain text when edited by admin").

[feladat @ 89] Fix documentation on i18n.

[feladat @ 88] Bugfix. When viewing the details of a slave zone, an error was shown if the ip addresses of it's master nameserver was set (instead of showing the error if there was none set. Reported: Maarten te Paske.