Move transferring request trackers to RequestTracker.
Call handler tracker through UIDTag, and auto-unlock it when the UIDTag is unlocked.
Call add/removeTransferringSender through RequestTag.
Track whether already unlocked transfer sending.
Check requestSender
Auto-unlock on unlockHandler for transferring request senders.
Key checks
IllegalStateException, absolutely not allowed to call senderTransferBegins before setting sender.
A bit more robust.
Make variables private.
Make variable final.
Synchronization.
Synchronization.
Include unlockHandler() in handlerThrew()
Update default bookmarks.
Only insert the flag <img> if we have the flag. We don't have all of them.
Cleaner implementation with a cache on the Country.
Rename confusingly named variable
Check the MIME type as soon as we have it, even if it is application/octet-stream. Pass the ClientMetadata, not the String metadata.
Bugfix prev commit.