Improved separation of test harness messages

Major tidy up of test harness and lifecycle methods

Moved test harnesses into separate _test.py modules

More representative synthetic data added to FSK receive test

Poked a synthetic switch on message down the MIHO005 receive pipeline

Started to flesh out the MiHome receive pipeline

Spec'ed interface for OOK decoder

Deprecated Messages due to import race with Devices. ...

Template messages (which are cloned with create_message) now in Devices.

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

More design on the tx/rx and air_interface pipeline

Renamed encoder as TwoBit, as it encodes two bits per byte. ...

This is the encoding protocol used with legacy OOK devices

Started to plan out the tx/rx pipeline for payloads and message buffers

Initial design of a message Router

Capabilities of devices turned into flags, with query method in base class

Mock registry store created, auto_create is working

Documented requirement for a simple persistent data store for the Registry

Started to implement device classes code. ...

Simple mocking interface now working.

Method signatures for Registry sketched out

Initial design for enhanced persistent registry done

Some ideas about device registration added

Method signatures for device classes added

Started to flesh out device classes proposed interfaces

Started to flesh out design thinking of device classes

Done a requirements and design pass of the device classes idea