* Refactor shouldUpdateScroll passing
So far, shouldUpdateScroll has been manually passed down from the very top of
the React component hierarchy even though it is a static function common to
all ScrollContainer instances, so replaced that with a custom class extending
ScrollContainer.
* Generalize “press back to close modal” to any modal and to public pages
* Fix boost confirmation modal closing media modal
* Make the area to the left “Show Thread” also expand the toot in Web UI
* Clicking the left part of a conversation with the avatars now opens it in Web UI
* Add conversations API
* Add web UI for conversations
* Add test for conversations API
* Add tests for ConversationAccount
* Improve web UI
* Rename ConversationAccount to AccountConversation
* Remove conversations on block and mute
* Change last_status_id to be a denormalization of status_ids
* Add optimistic locking
* Action/reducer for changing column settings takes a path and a value
instead of a javascript object
* Settings menu version and column headline version working simultaneously
* remove column headline entirely
* remove css for headlines that aren't possible now
* Remove commented out code from unfruitful attempt at this feature
* Give direct timeline its own column settings bc it doesn't have a media only option
* Fix typo in public timeline code that was preventing per-column settings from working properly
* Fix codeclimate issues
* Missing semicolons
* Use redux state to set onlyMedia, let that do the update instead of a callback. Consequently, unpinned setting works without history modification
* Unused import
