Ash auger rewrite continued

Almost ready for testing.
* Changed enumerated control/state values to macros.
* Renamed AshAugerSetMode() to AshAugerSwitchMode() to reflect the
semantics of the function.
* Added AshAugerStart() and AshAugerStop() for manual starting and
stopping of the ash auger.
* Moved the ADC structure into the adc library.
* Fixed a bug in the over-current accumulator that caused over/under
flow of the accumulator.
* Basic checking for H-bridge driver faults is implemented, but needs
improvement.
* Auger status display is removed until I can write a better API for
getting auger state.