Add direct-access methods to the base Device class, so that there's a common way of talking to drivers regardless of which of the specialised classes they derive from.

Make the Device destructor public and virtual, so that arbitrary devices can be deleted. Likewise for classes that derive from it.

Make Device::init public so that arbitrary devices can be initialised after being returned by factories.

Move NuttX configurations out of the NuttX tree proper. This reduces the diffs we have to carry against the NuttX upstream repo to just our local patches to the NuttX code itself.

ETS airspeed and MEAS airspeed combined driver

Implemented config command, fixed a number range set / get issues for some sensor drivers, fixed gyro calibration

Implemented new, simple system boot config and sane default value system