* track notifTimelineSet on MatrixClient
* stop Rooms from tracking notifTimelineSet as they don't need to
* Implement client.paginateNotifTimelineSet
* make Events store their pushActions properly
* insert live notifs directly into the notifTimelineSet in /sync, ordering by origin_server_ts.
- to make way for alternative encryption algorithms. We now store an encryption
object for each room, rather than referring to sessionstore on each event.
Also a little light tidying to the jsdocs.
In TimelineWindow.paginate, keep a count of the number of API requests we have
made, and bail out if it gets too high, to ensure that we don't get stuck in a
loop of paginating right back to the start of the room.
If we somehow end up in a situation where calling /messages returns a load
of messages, but none of them are new, then currently we start calling
/messages again and again in a tight loop. This is bad, so fix it.
