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

Helmo authored Sep 24, 2019 and Till Brehm committed Sep 24, 2019

Some form of inheritance might be nice to reduce the amount of duplication in these files.

Some were already in English, most were still in German.

- removed separate rspamd greylisting setting for policy and respect mail user/alias/forward/catchall setting for greylisting, fixes #5379

This reverts commit c97bed44.

Added remote functions config_value_get, config_value_add, config_value_update, config_value_replace and config_value_delete to access the sys_config key / value store in ISPConfig from remote api.

Add description text for logging options.