Refactored usages of raw message to use Message() ...

Removed all usages of showMessage, alterMessage

Improved separation of test harness messages

Major tidy up of test harness and lifecycle methods

Commissioned a tx path for MiHome adaptor Plus. ...

This is a temporary path, but it generates the correct message

LegacyDevice tx path commissioned end to end

Most of the OnAir interface coded or spec'ed now

Implementation checklist added for OnAir

Method signatures defined for OnAir adaptors

Spec'ed out responsibilities of OnAir interfaces

Placeholder added to architecture for radio interface adaptors