Purge the LOGLEVEL_INFO constant to avoid `Use of undefined constant` warnings

See merge request !873

Add support for chrooted php-fpm, implements #3220

See merge request !870

Panel reverse proxy

See merge request !871

Fix login_as / logout_from workflow forms

See merge request !872

with stored username/passwords and ignore the "value" attribute on post.

Start checks against local sites list for allowed reverse proxy forwards

First workflow for allow reverse proxy with different site names
for ispconfig panel.

TODO: Allow only for sites known to the system itself instead
of all or none.

Add descriptive comments to table definition

See merge request !862

Add incron_plugin, fixes #5218

See merge request !864

If the plugin runs at the end, and you are deleting a Site, the deletion
will not run completely because the trigger file still exists

- reduced duplicate code in dns remoting function

Add support for powerdns 4.x, fixes #5223

See merge request ispconfig/ispconfig3!865