- add support for version negotiation upon connecting
  this is a new feature from stomp 1.1
- implement protocol version negotiation
- send host when given
- debug protocol negotiation
- implement NACK frame
- refactor subscriptions
- hand over wire handling to StompSubscription itself
- convert to using namespaces
- namespace conversion fixes
- more work for subscriptions
- QA: add apidoc
- implement org.codehaus.stomp.Transaction
- add test coverage
- refactor tests to pull up setUp() to base
  while introducing base test
- initial work towards Message class
- work on messages
- introduce Header "value" interface
- implement tracking subscriptions in connection
- add subscription registry
- implement message subscription lookup
- add test coverage
- implement ack/nack on Message class
- add test coverage
- implement message sending
- introduce Header constants
- fix fatal
- add Message::toString()
- implement resending a received message
- implement keeping custom headers
- add test coverage