QPID-????: Tidy up
- Remove unused function getBuffered() of ConnectionOutputHandler
- Stop SessionContext and AggregateOutput from needlessly implementing
  the OutputControl interface
QPID-4854: Make the protocol negotiation timeout actually relate to
the protocol negotiation!
QPID-????: Remove unused members in Connector interface
QPID-????: Tidy-up remove OutputHandler and directly use FrameHandler
QPID-????: Remove deprecated and unused federation property
QPID-????: Remove unused function
QPID-????: Remove unused method
QPID-????: Remove unused Connection ErrorListener interface
- was only used by removed cluster support
QPID-????: Removed TimeoutHandler interface as it was really unused
QPID-????: Tidy up broker::Connection
- Clean up code for accounting for sent frames
- merged Connection and ConnectionState into Connection