Merged revisions 3922-3958 from stable branch.

install/dist/lib/fedora.lib.php

install/dist/lib/opensuse.lib.php

install/sql/incremental/upd_0050.sql

install/sql/ispconfig3.sql

install/tpl/apache_ispconfig.conf.master

install/tpl/apache_ispconfig.vhost.master

install/tpl/config.inc.php.master

interface/lib/lang/cz.lng

interface/lib/lang/pl.lng

interface/web/admin/form/system_config.tform.php

interface/web/admin/language_complete.php

interface/web/admin/lib/lang/ar_server_config.lng

interface/web/admin/lib/lang/bg_server_config.lng

interface/web/admin/lib/lang/br_server_config.lng

interface/web/admin/lib/lang/cz.lng

interface/web/admin/lib/lang/cz_directive_snippets.lng

interface/web/admin/lib/lang/cz_directive_snippets_list.lng

interface/web/admin/lib/lang/cz_firewall.lng

interface/web/admin/lib/lang/cz_firewall_list.lng

interface/web/admin/lib/lang/cz_groups.lng