Conflicts:
	synapse/notifier.py

Conflicts:
	synapse/notifier.py

SYN-375 - Lots of unhandled deferred exceptions.

Improvement to performance of presence event stream handling

Preserving logging contexts

Backfill support

Update the end_token correctly, otherwise the token doesn't advance and the client gets duplicate events

SYN-377: Make sure that the event is marked as persisted from the main thread.

SYN-377: Make sure that the StreamIdGenerator.get_next.__exit__ is called from the main thread after the transaction completes, not from database thread before the transaction completes.

Make get_current_token accept a direction parameter, which tells whether the source whether we want a token for going 'forwards' or 'backwards'

Fix 500 on push rule updates.

Hotfixes v0.9.0 r3