Added a test mode to test all 16 patterns of legacy control messages. ...

Run legacy.py and try numbers 0 to F in learning mode.
In theory you should be able to select 4 different switch addresses
plus an 'all addresses', but I can't get this to work on my 7 plugs,
they all respond as switch number 1 regardless of what code I send
in learning mode.

Attempts to get multiple device addresses working. ...

Seems to be a discrepancy between documentation and sample C code.
Stopping here until I get this clarified.

Renamed modulator as encoder