Support °F as well as °C

[brentru]

Per adafruit/Wippersnapper_Protobuf#109, we'd like components to be able to support a selectable ambient or object temperature of °F. This would be considered as a new "unit".

[tyeth]

I think we need to add some calculated fields/outputs per sensor type. That's what *F is, so then any existing temp sensor gets *F, and a fusion device (like one providing temp+humidty) can provide VPD(vapour pressure deficit) / Dew-point solving #71 and other future needs based off of calculations from the fusion sensor/device. I think custom options at the are probably too much work, as you can take the data if needed out of adafruit IO, but common needs for the sensor / data type make sense and would dramatically reduce the burden if done at the sensor-type level

[brentru]

@tyeth That's what we're doing in #75.

VPD is not on my high priority list right now, but, we can add additional types for VPD/sensor fusion in the future, in the same method that we're adding *F.

[tyeth]

Thank you, I shall follow it keenly :) I care little right now for VPD, but it's on my greenhouse priority list (way down there)

[brentru]

Resolved in adafruit/Adafruit_Wippersnapper_Arduino#324, please use Beta 51 and up for this functionality to appear!