Add new file to display current kernel info. Related to comment !789 (comment 63987)

Add description text for logging options.

Optimized prosody configuration for full conversations.im feature compartibility including full OMEMO support

Fixed#5019 LE cert problem in mirror setups. This patch disables the creation of Let's encrypt SSL certs on mirrored slave servers.

#5030

Added a third parameter to $app->log() function in server part to turn off logging to database and use this option in mysql lib to not log any server side SQL errors to the database.

- Fixed #5027 add support for PHP 7.1 and 7.2 on nginx servers in apps vhost.
- suppress some warnings in simplepie.inc.php

global option to enable pagespeed with nginx - allows to enable pagespeed even if no webserver-config is selected

- fixed backups not downloadable on multiserver slave, fixes #4973