Vehicle settings discussion

[buxtronix]

I have spent a little time trying to figure out the way the "Vehicle Settings" (per the OEM app) are communicated.

I have some initial code and notes in https://github.com/buxtronix/phev2mqtt/blob/settings/protocol/SETTINGS.md

Basically, the car sends settings using register 0x16, and updates to these are sent by the app via 0x0f. Updating
the settings is easy - it's two bytes - one is the setting, the other is the new value.

However decoding what comes from the car is harder. If I change a setting, I can see relevant bits change in what
is returned from 0x16, though figuring out the whole structure is harder - in particular exactly how we know what
settings are conveyed in a particular 0x16 packet...going to need to figure this out a bit more..