INT-2830 Resolve Class Tangle

* MessageGroupStore <-> MessageGroupCallback
  - Change callback to be an inner interface of the MGS.
* INT-2829 Fix Class Tangle in IP Module
  - 3 way tangle between TcpSender, TcpConnection, TcpMessageMapper
  - Clean up interfaces (remove setters); add top-level support classes for TcpConnection, TcpConnectionInterceptor.
* INT-2829 Remove TCP Package Tangle
  - tcp.connection <-> tcp.connection.support
  - Remove ...connection.support package - move classes to ...connection.
Merge pull request #719 from garyrussell/INT-2829

* garyrussell-INT-2829:
  INT-2830 Resolve Class Tangle