Message.get() implemented and tested with paramid keying

Started to think through a better message abstraction

Started to think through a better alterMessage ...

characters that can be used in an identifier need checking

Moved test harnesses into separate _test.py modules

Python 3 now supported. ...

Logger now stores apparent power and real power headings.
Logger now stores temperature from eTRV in csv file

Now displays receive time of incoming messages

Restructured switch.py so we have a tx-only test. ...

This is in preparation for pushing the FSK transmitter into radio.c

Started refactoring