Merged revisions 3960-4065 from stable branch.

install/dist/lib/centos52.lib.php

install/dist/lib/centos53.lib.php

install/dist/lib/debian60.lib.php

install/dist/lib/fedora.lib.php

install/dist/lib/gentoo.lib.php

install/dist/lib/opensuse.lib.php

install/lib/install.lib.php

install/lib/installer_base.lib.php

install/sql/incremental/upd_0051.sql

install/sql/incremental/upd_0052.sql

install/sql/incremental/upd_0053.sql

install/sql/incremental/upd_0054.sql

install/sql/ispconfig3.sql

install/tpl/apache_ispconfig.vhost.master

install/tpl/debian6_dovecot2.conf.master

install/tpl/debian_dovecot2.conf.master

install/tpl/debian_postfix.conf.master

install/tpl/fedora_dovecot2.conf.master

install/tpl/fedora_postfix.conf.master

install/tpl/gentoo_postfix.conf.master