Make sure that we check that events sent over /send_join, /send_leave, and
/invite, are correctly signed and come from the expected servers.

Remove repeated calls to config.stats_enabled.

Fix /keys/query API on workers.

The necessary getters were added only to the master store and not the
worker stores.

Turns out that fetching variables from the config object is expensive,
so doing it once at startup avoids unnecessary work.

Move schema delta files to the correct data store.

Add new boolean column to synapse_port_db

They were put in the global schema delta directory due to a bad merge.

The expected use case is to suppress MAU limiting on small instances

Fix import paths in synapse_port_db

Make `synapse_port_db` correctly create indexes in the PostgreSQL database, by having it run the background updates on the database before migrating the data.

To ensure we're migrating the right data, also block the port if the SQLite3 database still has pending or ongoing background updates.

Fixes #4877 

Add a linting script that enforces all boolean values in the default config be lowercase.

This has annoyed me for a while so I decided to fix it.

Refactor storage layer to support multiple databases

Cross-signing [3/4] -- uploading signatures edition

The synapse demo was a bit flakey in terms of supporting federation. It turns out that if your computer resolved `localhost` to `::1` instead of `127.0.0.1`, the built-in federation blacklist specified in `start.sh` would still block it, since it contained an entry for `::/127`. Removing this no longer prevents Synapse from contacting `::1`, federation works again on these boxes.

Added database owner authentication with `sudo` when `su` does not work

This is in preparation for having multiple data stores that offer
different functionality, e.g. splitting out state or event storage.

* Delete format_tap.py

This python implementation of a tap formatting library for buildkite has been
replaced with a perl implementation as part of the matrix-org/sytest repo,
which is specific to sytest's language, not that of any one homeserver's.

... again?  How did you make it disappear, git?