ExecStopPost should allow us to clean up (docker kill + docker rm)
even if the ExecStart (docker run ..) command failed, and not just after
a graceful service stop was initiated.

Source: https://www.freedesktop.org/software/systemd/man/systemd.service.html#ExecStopPost=

Enables optional access to Etherpad's web-UI. This is useful for
managing Etherpad plugins.

Among other things, plugins makes it easy to manage/delete pads if you
install the adminpads2 plugin.

Extend the config template with the lines added in the past year

Until now, we were leaving services "enabled"
(symlinks in /etc/systemd/system/multi-user.target.wants/).

We clean these up now. Broken symlinks may still exist in older
installations that enabled/disabled services. We're not taking care
to fix these up. It's just a cosmetic defect anyway.

Signed-off-by: Ahmad Haghighi <haghighi@fedoraproject.org>

This reverts commit fd3d48bb6d.

Normally this environment variable gets referred to from `settings.json.docker`,
but we have our own full configuration, which hardcodes `"trustProxy": true`,
thus making this useless.

This has been pointed out here:
fd3d48bb6d (commitcomment-47403097)

The official Etherpad Docker image has no support for sqlite3 databases.

don't bind to any host port if nginx_proxy is used
only bind to localhost if it's not used

The default scalar.vector.im integrations manager doesn't support custom
URL's for etherpad, therefore Dimension needs to be enabled.