moves non-runtime dependencies out of synapse.python_dependencies (test and lint)

This change adds a note and a few lines of configuration settings for Apache users to disable ModSecurity for Synapse's virtual hosts. With ModSecurity enabled and running with its default settings, Matrix clients are unable to send chat messages through the Synapse installation. With this change, ModSecurity can be disabled only for the Synapse virtual hosts.

Fixes: #8359 

Trying to reactivate a user with the admin API (`PUT /_synapse/admin/v2/users/<user_name>`) causes an internal server error.

Seems to be a regression in #8033.

Add an admin API to read entries of table `event_reports`. API: `GET /_synapse/admin/v1/event_reports`

* Create a new function to verify that the length of a device name is
under a certain threshold.
* Refactor old code and tests to use said function.
* Verify device name length during registration of device
* Add a test for the above

Signed-off-by: Dionysis Grigoropoulos <dgrig@erethon.com>

Synapse 1.20.0rc5 (2020-09-18)
==============================

In addition to the below, Synapse 1.20.0rc5 also includes the bug fix that was included in 1.19.3.

Features
--------

- Add flags to the `/versions` endpoint for whether new rooms default to using E2EE. ([\#8343](https://github.com/matrix-org/synapse/issues/8343))

Bugfixes
--------

- Fix rate limiting of federation `/send` requests. ([\#8342](https://github.com/matrix-org/synapse/issues/8342))
- Fix a longstanding bug where back pagination over federation could get stuck if it failed to handle a received event. ([\#8349](https://github.com/matrix-org/synapse/issues/8349))

Internal Changes
----------------

- Blacklist [MSC2753](https://github.com/matrix-org/matrix-doc/pull/2753) SyTests until it is implemented. ([\#8285](https://github.com/matrix-org/synapse/issues/8285))

1.19.3

Synapse 1.19.3 (2020-09-18)
===========================

Bugfixes
--------

- Partially mitigate bug where newly joined servers couldn't get past
events in a room when there is a malformed event.
([\#8350](https://github.com/matrix-org/synapse/issues/8350))

Add a new admin API `GET /_synapse/admin/v1/users/<user_id>/joined_rooms` to
list all rooms where a user is a member.

Signed-off-by: Olivier Wilkinson (reivilibre) <olivier@librepush.net>
Co-authored-by: Patrick Cloke <clokep@users.noreply.github.com>

* Fix _set_destination_retry_timings

This came about because the code assumed that retry_interval
could not be NULL — which has been challenged by catch-up.

This converts calls like super(Foo, self) -> super().

Generated with:

    sed -i "" -Ee 's/super\([^\(]+\)/super()/g' **/*.py

Add ability for ASes to /login using the `uk.half-shot.msc2778.login.application_service` login `type`.

Co-authored-by: Patrick Cloke <clokep@users.noreply.github.com>

This is a bit of a hack, as `_check_sigs_and_hash_and_fetch` is intended
for attempting to pull an event from the database/(re)pull it from the
server that originally sent the event if checking the signature of the
event fails.

During backfill we *know* that we won't have the event in our database,
however it is still useful to be able to query the original sending
server as the server we're backfilling from may be acting maliciously.

The main benefit and reason for this change however is that
`_check_sigs_and_hash_and_fetch` will drop an event during backfill if
it cannot be successfully validated, whereas the current code will
simply fail the backfill request - resulting in the client's /messages
request silently being dropped.

This is a quick patch to fix backfilling rooms that contain malformed
events. A better implementation in planned in future.

Instead of just using the most recent extremities let's pick the
ones that will give us results that the pagination request cares about,
i.e. pick extremities only if they have a smaller depth than the
pagination token.

This is useful when we fail to backfill an extremity, as we no longer
get stuck requesting that same extremity repeatedly.

c.f. #8295 for rationale

Lint dependencies can now be installed with pip install -e ".[lint]"

This should help keep the version in sync between tox and documentation.

Dendrite's implementing MSC2753 over at https://github.com/matrix-org/dendrite/pull/1370 to prove the implementation for MSC purposes, and so sytest has sprouted tests for it over at https://github.com/matrix-org/sytest/pull/944. But we don't want them to run on synapse until synapse implements it.

This reduces duplication of the admin prefix in regular expressions.

Replaced with less buggier control flow

Synapse 1.20.0rc4 (2020-09-16)
==============================

Synapse 1.20.0rc4 is identical to 1.20.0rc3, with the addition of the security fix that was included in 1.19.2.