QPID-4905: 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-4905: Remove unused members in Connector interface
QPID-4905: Tidy-up remove OutputHandler and directly use FrameHandler
QPID-4905: Remove deprecated and unused federation property
QPID-4905: Remove unused function
QPID-4905: Remove unused method
QPID-4905: Remove unused Connection ErrorListener interface
- was only used by removed cluster support
QPID-4905: Removed TimeoutHandler interface as it was really unused
QPID-4905: Tidy up broker::Connection
- Clean up code for accounting for sent frames
- merged Connection and ConnectionState into Connection