This is the first tranche of support for room versioning. It includes:
 * setting the default room version in the config file
 * new room_version param on the createRoom API
 * storing the version of newly-created rooms in the m.room.create event
 * fishing the version of existing rooms out of the m.room.create event

Returns an M_CONSENT_NOT_GIVEN error (cf
https://github.com/matrix-org/matrix-doc/issues/1252) if consent is not yet
given.

turns out we need to reuse this, so it's better in the config class.

When a user first syncs, we will send them a server notice asking them to
consent to the privacy policy if they have not already done so.

The imports were shuffled around a bunch in py3

Signed-off-by: Adrian Tschira <nota@notafile.com>

These worked accidentally before (python2 doesn't complain if you
compare incompatible types) but under py3 this blows up spectacularly

Signed-off-by: Adrian Tschira <nota@notafile.com>

This has no effect on python2

Signed-off-by: Adrian Tschira <nota@notafile.com>

... instead of creating our own special SQLiteMemoryDbPool, whose purpose was a
bit of a mystery.

For some reason this makes one of the tests run slightly slower, so bump the
sleep(). Sorry.

Configure the connectionpool used for unit tests to run the `on_new_connection`
function.

This isn't used, and looks thoroughly bitrotted.

Add federation_domain_whitelist

gives a way to restrict which domains your HS is allowed to federate with.
useful mainly for gracefully preventing a private but internet-connected HS from trying to federate to the wider public Matrix network

Fix flakiness in the UTs caused by the user_directory being updated in the
background

what could possibly go wrong

- allows sysadmins the ability to lock down their servers so that people can't
send their users room invites.

Instead of every time a new email pusher is created, as loading jinja2
templates is slow.

Allows delegating the password auth to an external module. This also
moves the LDAP auth to using this system, allowing it to be removed from
the synapse tree entirely in the future.