- fixed rspamd settings
- fixed errors in webserver plugin
- fixed error in dkim domain handling

Update nginx_ispconfig.vhost.master to change the same in nginx_ispconfig.vhost.master and to change the same in installer_base.lib.php as well.

The cipher suites are only set now for ISPConfig's own vhost, the intermediate security profile from Mozilla is used here.

ISPConfig itself does not read nor interpret this header, but there might be other
server components like PHP that might interact with it so I'll disable it just to be sure.

This reverts commit 008ef889.

Fixed a regex in ispconfig and apps vhost for nginx: https://www.howtoforge.com/community/threads/possible-bug-in-a-nginx-regex.68948/

avoid 400 bad request error if ssl is enabled and interface is accessed with http instead of https. Instead redirect to the requested page with https at the beginning of the URL.

According to FS#1982

replaced "listen ... ssl;" through "ssl on;" in nginx (ispconfig.vhost) in case that ssl is used for ispconfig

- Changed FastCGI buffers for ISPConfig nginx vhost because otherwise you get "upstream sent too big header while reading response header from upstream" on OpenSUSE.
- Added 502 error page ("Bad Gateway").
- Added "fastcgi_intercept_errors on;" to nginx vhost template so that ISPConfig's error pages are displayed instead of the default nginx ones.

- Removed ufw configuration from installer to avoid "PHP Notice:  Undefined index: ufw in /tmp/trunk/install/install.php on line 251".
- Changed phpMyAdmin location in ISPConfig nginx vhost to allow phpmyadmin and phpmyadmin/ (with and without trailing slash).