message: Rename variables, more comments
diff: @@ -507,7 +507,7 @@ var TimelinePanel = React.createClass({
  // if no client or client is guest don't send RR or RM
  if (!cli || cli.isGuest()) return;
  - let shouldSendRR = true;
  + let shouldSendReadReceipt = true;
  var currentReadUpToEventId = this._getCurrentReadReceipt(true);
  var currentReadUpToEventIndex = this._indexForEventId(currentReadUpToEventId);
  @@ -526,26 +526,30 @@ var TimelinePanel = React.createClass({
  //
  if (currentReadUpToEventId && currentReadUpToEventIndex === null &&
  this._timelineWindow.canPaginate(EventTimeline.FORWARDS)) {
  - shouldSendRR = false;
  + shouldSendReadReceipt = false;
  }
  var lastReadEventIndex = this._getLastDisplayedEventIndex({
  ignoreOwn: true
  });
  if (lastReadEventIndex === null) {
  - shouldSendRR = false;
  + shouldSendReadReceipt = false;
  }
  var lastReadEvent = this.state.events[lastReadEventIndex];
  - shouldSendRR = shouldSendRR &&
  - (lastReadEventIndex > currentReadUpToEventIndex &&
  - this.last_rr_sent_event_id != lastReadEvent.getId());
  + shouldSendReadReceipt = shouldSendReadReceipt &&
  + // Only send a RR if the last read Event is ahead in the timeline relative to
  + // the current RR event.
  + lastReadEventIndex > currentReadUpToEventIndex &&
  + // Only send a RR if the last RR set != the one we would send
  + this.last_rr_sent_event_id != lastReadEvent.getId();
  - const shouldSendRM = this.last_rm_sent_event_id != this.state.readMarkerEventId;
  + // Only send a RM if the last RM sent != the one we would send
  + const shouldSendReadMarker = this.last_rm_sent_event_id != this.state.readMarkerEventId;
  // we also remember the last read receipt we sent to avoid spamming the
  // same one at the server repeatedly
  - if (shouldSendRR || shouldSendRM) {
  + if (shouldSendReadReceipt || shouldSendReadMarker) {
  this.last_rr_sent_event_id = lastReadEvent.getId();
  this.last_rm_sent_event_id = this.state.readMarkerEventId;
  