* optimize direct timeline
* fix typo in class name
* change filter condition for direct timeline
* fix codestyle issue
* revoke index_accounts_not_silenced because direct timeline does not use it.
* revoke index_accounts_not_silenced because direct timeline does not use it.
* fix rspec test condition.
* fix rspec test condition.
* fix rspec test condition.
* revoke adding column and partial index
* (direct timeline) move merging logic to model
* fix pagination parameter
* add method arguments that switches return array of status or cache_ids
* fix order by
* returns ActiveRecord.Relation in default behavor
* fix codestyle issue
* 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
