* Add more granular OAuth scopes

* Add human-readable descriptions of the new scopes

* Ensure new scopes look good on the app UI

* Add tests

* Group scopes in screen and color-code dangerous ones

* Fix wrong extra scope

* 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

Use Rails smart boolean cast to account for values such as "f",
"0", "false", etc. Previously, if a param was present in the request,
it would count as true.

* Fix regeneration marker not being removed after completion

* Return HTTP 206 from /api/v1/timelines/home if regeneration in progress
Prioritize RegenerationWorker by putting it into default queue

* Display loading indicator and poll home timeline while it regenerates

* Add graphic to regeneration message

* Make "not found" indicator consistent with home regeneration

* Add structure for lists

* Add list timeline streaming API

* Add list APIs, bind list-account relation to follow relation

* Add API for adding/removing accounts from lists

* Add pagination to lists API

* Add pagination to list accounts API

* Adjust scopes for new APIs

- Creating and modifying lists merely requires "write" scope
- Fetching information about lists merely requires "read" scope

* Add test for wrong user context on list timeline

* Clean up tests

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

* Move ApiController to Api/BaseController

* API controllers inherit from Api::BaseController

* Add coverage for various error cases in api/base controller

- Increase coverage to exercise all parts of each action
- Move into namespace to share common code
- Misc refactor of each action for smaller methods, simpler code