[Snails] QToolButton for message attachments.
[Snails] Added debug print for QPointers.
[Snails] More const-correctness.
[Snails] Added debug output op for std::shared_ptr.
[Snails] Added Concurrent exceptions.
[Snails] Added QFutureInterface promise to TaskQueueItem.
[Snails] Report on TaskQueueItem's promises.
[Snails] AccountThread::AddTask() now returns the future.
[Snails] Return the future from SendMessage().
[Snails] Rethrow message sending exception.