Conflicts:
	tests/handlers/test_room.py

Send list of typing user IDs as 'user_ids' list within 'content', so that m.typing stream events have a toplevel content, for consistency with others

Actually auth-check to ensure people can only send typing notifications for rooms they're actually in

Conflicts:
	setup.py

Media repository

Allow only one download for a given image at a time, so that we don't end up downloading the same image twice if two clients request a remote image at the same time