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