Only show voice call button if there are exactly 2 members in the room. Also hide the somewhat user unfriendly call state.

Change call signalling messages to be their own types of room events rather than room messages with different msgtypes: room messages should be things that the client can display as a unit message to the user.

Fix a couple of bugs in presence handler related to pushing updatesto the correct user. Fix presence tests.

Conflicts:
	webclient/room/room-controller.js

Added a timeout(40s) to $http stream requests (/events) in order to be notified by an error when there is a network issue. Thus, we can retry with a new request.

Recents update: do not care of events coming from the past (they are fired when doing pagination of room messages in the past)

Don't query the rooms members table so much by using the new notifier api that allows you to specify room_ids to notify.

Start fleshing out architecture section. Moar .rst formatting! Reword some copypastaed sections to be terser.

Conflicts:
	synapse/handlers/presence.py