Added option to only allow guests with a global password

Also fixed an error in valid_admin() introduced in the previous version

lang_de.php

@@ -54,6 +54,7 @@ $I=array(
 	'msgclean' => 'Raum geleert',
 	'nick' => 'Nickname:',
 	'pass' => 'Passwort:',
+	'globalloginpass' => 'Globales Passwort:',
 	'login' => 'Anmelden',
 	'admfunc' => 'Administrative Funktionen',
 	'allguests' => 'Alle Gäste',
@@ -74,6 +75,7 @@ $I=array(
 	'guestallow' => 'Erlauben',
 	'guestwait' => 'Mit Warteraum erlauben',
 	'adminallow' => 'Moderator-Erlaubnis benötigen',
+	'globalpass' => 'Globales Passwort',
 	'guestdisallow' => 'Verweigern',
 	'addsuguest' => 'Anwerber hinzufügen',
 	'register' => 'Registrieren',