Renamed the 'Legacy' classes to have their library prefix (avoid confusion)
Removed the legacy Objective C Thread code (pulled only the NSCoding stuff into the 'SMKLegacy' type)
Got mentions working again
Got typing indicators working again
Got the notification sound and preview preferences working
Fixed a few issues with attachment image loading
Fixed an issue where enum settings weren't getting stored correctly
Refactored the SignalApp class to Swift
Fixed a horizontal alignment issue in the ConversationTitleView
Fixed an issue where expiration timer update messages weren't migrated or rendering correctly
Fixed an issue where expiring messages weren't migrated correctly
Fixed an issue where closed groups which had been left were causing migration failures (due to data incorrectly being assumed to be required)
Shifted the Legacy Attachment types into the 'SMKLegacy' namespace
Moved all of the NSCoding logic for the TSMessage
Refactored the AppDelegate from Objective C to Swift
Updated the HomeVC to use GRDB
Refactored a number of the Job types to be driven via GRDB and the new JobRunner
Fixed a bug where the LinkPreviewView wouldn't render correctly in dark mode
Added migrations for contacts and started working through thread migration (have contact and closed group threads migrating)
Deprecated usage of ECKeyPair in the migrations (want to be able to remove Curve25519Kit in the future)