Add waterfurnace platform
This adds support for waterfurnace geothermal systems. This is
implemented as a component as there will eventually be some active
control elements. This is not done as a climate platform because
geothermal systems work best when set at a constant temperature as
they are tuned to keep within 0.5 degrees F of a setpoint, and large
temperature shifts are slow and expensive.
This is done in the Data + Sensors model, with the Data component
having a regular update thread. That thread needs to call the read()
function at least every 30 seconds otherwise the underlying websocket
is closed by the server.
Sean Dague