Adding more tests to MailboxSpec so that we know they follow the contract ;)
Merge pull request #1303 from akka/wip-add-more-mailbox-tests-√

Adding more tests to MailboxSpec so that we know they follow the contrac...
clarify watch() idempotency (Scala)
clarify watch() idempotency (Java)
io: handle half-closed connection when peer closed first

This allows to send data back to the peer even if the peer already has sent
EOF/FIN as specified for TCP. To fully close a connection, the handler has
to close its side of the connection now actively once it is finished with
writing even if it received a `PeerClosed` message before.
TcpConnection: use pattern matching
Tcp: hide support for half-closed connections behind Register.keepOpenOnPeerClosed