Fixed a number of scrolling behaviours in the ConversationVC
Fixed a bug with the PagedDataObserver when observing associated data (multiple associations with a single paged result were broken)
Fixed a bug with the PagedDataObserver where it would trigger updates for new entries even if the user is offset from the latest data
Fixed a bug where marking as read wasn't working properly
Fixed a bug where outgoing messages were being considered unread
Added an error state for a failed attachment send
Renamed a few types for clarity
Resolved a bunch of TODOs