Add EventHub, add fav, reblog events, improve timelines (#562)
* Add AppStore, add fav, reblog events
* Add events, add handling to Timeline
* Add event handling to Notifications
* Mostly finish events
* Fix unsubscribing
* Cleanup timeline
* Fix newStatusEvent in thread, fix deleteEvent
* Insert new toots only in specific timelines
* Add missing else
* Rename AppStore to EventHub
* Fix tests
* Use DiffUtils for timeline
* Fix empty timeline bug. Improve loading placeholder
* Fix AsyncListDiff, loading indicator, "load more"
* Timeline fixes & improvements.
Fix infinite loading. Remove spinner correctly.
Don't refresh timeline without need.