Added Global Setting to Server config tab to
  - Enable & Disable the feature
  - Set the Proxy HTTP & HTTPS Ports

Added Per site level switch to enable and disable feature (Located in the Web Tab under the advanced section)

Added Apache2 and Nginx vhost updates to enable proxy_protocol on the listen lines

Added New database column to web_domain called "proxy_protocol" to enable site level config (Patch file Added upd_0089.sql)

Updated the Base Table SQL file to include "proxy_protocol" field

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

Changed apache mod_proxy_fcgi configuration in vhost.conf.master from ProxyPassMatch to SetHandler so we can wrap the config directive it into <Directory ...> to avoid side affects with globally installed applications like phpmyadmin and roundcube.

After enabling "Rewrite HTTP to HTTPS" and "Lets Encrypt SSL" the RewriteCond and RewriteRule got on the same line, becourse of an failing newline

Adding SSLStaplingCache shmcb:/var/run/ocsp(128000) to vhost template conf if apache version >= 2.4 and ssl enabled

- backported patches

- added intermediate SSL security profile (see https://mozilla.github.io/server-side-tls/ssl-config-generator/)
- TODO: admin option to choose between intermediate (default) and modern

Note: The mod_proxy_fcgi that ships with CentOS and Ubuntu does not support sockets yet, so all php-fpm connections are done by IP.

- changed hhvm handling to match stable branch (FilesMatch in Directory sections) - added changes from stable accordingly

Revert "Fixed: FS#3581 - Website unaccessible under some circumstances when using seo redirection *.domain to www.domain"

This reverts commit 5742e4c9.

Fixed: FS#3581 - Website unaccessible under some circumstances when using seo redirection *.domain to www.domain
(only for apache2, nginx still to do)