Read markers should be synchronised across clients

- Support jump to the last unread message.

vector-im/riot-meta#8

Riot/Model/Room/RoomDataSource.h

@@ -1,5 +1,6 @@
 /*
  Copyright 2015 OpenMarket Ltd
+ Copyright 2017 Vector Creations Ltd
 
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
@@ -26,4 +27,9 @@
  */
 @property(nonatomic) NSString *selectedEventId;
 
+/**
+ Tell whether the initial event of the timeline (if any) must be marked. Default is NO.
+ */
+@property(nonatomic) BOOL markTimelineInitialEvent;
+
 @end