Merge branch 'develop' into rav/flatten_sync_response

CHANGES.rst

scripts/synapse_port_db

synapse/__init__.py

synapse/api/auth.py

synapse/api/filtering.py

synapse/config/_base.py

synapse/handlers/account_data.py

synapse/handlers/auth.py

synapse/handlers/message.py

synapse/handlers/sync.py

synapse/rest/client/v2_alpha/sync.py

synapse/rest/client/v2_alpha/tags.py

synapse/storage/prepare_database.py

synapse/storage/schema/delta/26/account_data.sql

synapse/storage/tags.py

synapse/streams/events.py

synapse/types.py