Code port / refactor

- modelled Message as a distinct entity.

- message model data is now an array. Couldn't support repeating fields or maintain field order using maps.

- removed pipe and handlers.

- FIX keys are now never passed around or used in the system. Only convert from keys to field names and back at first entry and last exit point.

- Currently no Server code

- No tests. Need to implement Server and port test scripts.