Fix email flag interleaving
Updates the engine to support and use the IMAP STORE SILENT option, so that server's don't echo email flag updates to us, and the kind of interleaving described in #790 (closed) can't happen.
Fixes #790 (closed)
Updates the engine to support and use the IMAP STORE SILENT option, so that server's don't echo email flag updates to us, and the kind of interleaving described in #790 (closed) can't happen.
Fixes #790 (closed)