Signed-off-by: Silke Hofstra <silke@slxh.eu>

This reverts commit c31e375a.

Make sure that users' changes to the config files are preserved.

Fixes #4440.

* implement `reload` by sending the HUP signal

According to the 0.99 release info* synapse now uses the HUP signal to reload certificates:

> Synapse will now reload TLS certificates from disk upon SIGHUP. (#4495, #4524)

So the matrix-synapse.service unit file should include a reload directive.

Signed-off-by: Дамјан Георгиевски <gdamjan@gmail.com>

Rather than hardcoding a config which we always forget to update, generate it
from the default config.

In the debian package, make the virtualenv symlink python to /usr/bin/python3.X
rather than /usr/bin/python3. Also make sure we depend on the right python3.x
package.

This might help a bit with subtle failures when people install a package from
the wrong distro (https://github.com/matrix-org/synapse/issues/4431).

* remove dh_params and set better cipher string

turns out that 0.34.1.1+1 comes before 0.34.1.1+bionic (etc).

The version may only contain "~ 0-9 A-Z a-z + - ." (sorting in that order).

Option 1: replace "+" with something that sorts after +. Options are "-" (but
dpkg-source complains about that) or "." (but that would mean we couldn't
distinguish packaging-only changes from real changes).

Option 2: stick with + and just find something that sorts after 'xenial'. The
only options there are "-", "." (same problems as before), "z", and "+".

Hence, ++1. Sorry.

Otherwise people can't upgrade from matrix-synapse without removing it first

...  to allow installation alongside our matrix-synapse transitional package.

Make sure we don't put the _trial_temp directory in the package target
directory.

Fixes https://github.com/matrix-org/synapse/issues/4322

since #4298, the optional dependencies are no longer installed with a simple
`pip install .`, which meant that they were not being included in the debian
package.

The easy fix to that is dh_virtualenv --extras, but that needs dh_virtualenv
1.1...

Better follow our own release notes.