Reduce public method of `SyncTwitterClient` class
Change `SyncTwitterClientPlugin` protocol to singleton model
Remove unused protocol declaration
Remove unused interface
Change `STCPluginForTweetbotMac` to use `-[PTHTweetbotCursor indexOfTID:]`
Change to include latestID into notification
Change `STCPluginForTwitterMac` to observing more `ABUIScrollViewDelegate` methods
`STCPluginForTwitterMac` will not send position if scrolling is caused by syncing.
Version 0.2
Update README.md
Merge branch 'release/0.2'