Tested and tweaked for Python 3 support

Tested demos on real hardware. Works fine. ...

Observation: handling of incoming messages does not check registry,
it only checks the router, so if you don't have a device object
bound to it, it will be seen as unknown. Needs fixing, but not a high
priority.

Tested setup_tool.py on real hardware - works OK ...

Some tweaks required but now works fine

All test cases now run fine. ...

There is no capture/compare at the moment, so verification is manual

Rationalised all comment styles. ...

The double hash (##) is reserved for commented out lines of code.
The single hash (#) is reserved for normal comments.

Moved setup code from global scope of Registry to energenie.init() ...

This makes it possible to use the registry in test cases

Synthetic receive working in monitor_mihome.py

energenie.loop() written with FSK receiver connected to fsk_router

switch.py renamed as control_mihome.py, rewritten for new OO interface

legacy.py rewritten to use new device class interface

Added source files from first working tests