Task #8531: start and stop listening can now be used without -with- which defaults to start listening now. refactored some code and added support in RPC for multiple arguments.

Task #8531: Remove support for Binary message content and ensure Strings are always unicode when sent. Also make sure 'content' is first positional argument for EventMessage due to the way the message factory works. This breaks TreeStatusEvents.py which should use named arguments instead.

Task #8571: Initial import of messaging python libraries based on work from Marcel Loose for APERTIF.