Tiny tidy up

Started refactoring

Implemented a standalone switch exerciser demo. ...

Note this only really works with Adaptor Plus
(unless you seed the directory with your device id's first)

Started work on OOK support. ...

Ported C code into radio.py
Split out monitor and switch. Monitor.py is now just a monitor.
Switch.py needs more work to make it just a switch.
legacy.py will be a demo app for legacy (green button) devices.

Added rudimentary support for MIHO005 (HOUSE MONITOR) and MIHO013 (ETRV) ...

Fixed bug where eTRV sends an empty JOIN message that crashed the code
Added some extra fields to the CSV to support apparent power for House Monitor
Note: Voltage scaling on house monitor is incorrect.

Removed and tweaked a lot of trace messages to make it less noisy

Added a simple data logging to CSV capability

Added RESET at start to reset the radio to a known clean state. ...

Added a SWITCH ON/OFF message every 5 seconds.
Re-tested and reports now seem to be a reliable 10 seconds.

Improved message decoding. ...

Now builds a dictionary of seen devices.
Monitor FFFFFF messages removed, not needed.
Catches bad payloads and prints a warning rather than crashing.
Accepts and responds to a JOIN command.
Message and value encoders written and working.
Message and value decoders written and working.

Message decoder added. ...

Messages polled at a faster rate.
Now see unsolicited switch change messages from MiHome AdapterPlus.
Removed a lot of debug messages.
Real value decoding now working.

Improved encoding and decoding of OpenHEMS payloads. ...

Now uses pydict structures in the user app.
Encoding, encryption, decryption, and decoding done inside OpenHEMS.
This simplifies the application interface.

Added source files from first working tests