This fixes below bugs:

* addReply() had used native compare operator for string ids
  => descendants may appears at wrong position
* CONTEXT_FETCH_SUCCESS had added the focused status as the reply of the *first* status in ancestors, not last status.
  => descendants may also appears wrong position as well as correct position
* TIMELINE_UPDATE had added the status to replies of *itself* instead of replied status
  => browser will hangs if you open the status due to a circular reference

This allows to filter out replies in threads even if contexts of those
replies are not fetched.

* Added a timeline for Direct statuses
* Lists all Direct statuses you've sent and received
* Displayed in Getting Started
* Streaming server support for direct TL

* Changes to match other timelines in 2.0

Filtering the status collection wipes out even the profiles of muted and
blocked accounts. However, the behavior is inconsistent with the server-
side behavior.

* Move ancestors/descendants out of timelines reducer

* Refactor timelines reducer

All types of timelines now have a flat structure and use the same
reducer functions and actions

* Reintroduce some missing behaviours

* Fix wrong import in reports

* Fix includes typo

* Fix issue related to "next" pagination in timelines and notifications

* Fix bug with timeline's initial state, expandNotifications