Fixed: #4307 The new LE ssl cert paths introduced in ISPConfig 3.1.1 where not set in the nginx_vhost.conf.master

fixed placeholders in system_config_misc



See merge request !478

Various 3.1 fixes



See merge request !477

- fixed some smaller things in plugins for apache and nginx

Corrected typo in french



See merge request !476

Implemented #4271 Creating vHost Website Alias copies default index.html thus breaking the original site if it's based on index.php (or something not index.html)

XMPP Server Setup bugfix for 3.1

Content:
- replaced old dev default values in dns generation for XMPP domains by server name
- added datalog tokens for xmpp domains and users
- fixed DB query for XMPP authentication and user query
- added default values for all CSR fields, so they cannot be empty

There is still a new error with the authentication. The Auth script used to authenticate against the database should be spawned in its own process, but the auth module seems not to load it.  
Maybe it is a problem with new library versions released during the last year. I'm in contact with the metronome Devs to solve this problem.

In meantime, this bugfix will ensure that the servers are configured correctly.

See merge request !471

Fixes: 3878 + ipv6-prefix for mirror



See merge request !472