Add run method, that encapsulate any mainloop logic on behalf of the
client code. The setup/loop functions are passed via a HAL::Callbacks
interface. The AP_HAL_MAIN() macro should be kept as trivial as
possible.
This interface should be implemented by the existing vehicle objects. To
make easy for the examples (that don't have the equivalent of vehicle
objects), a FunCallbacks was added to bridge to the functions directly.
the idea of a separate console class was never really used, and just
added confusion in a HAL port. It also consumes some much needed ram
and flash space on APM2
* I'd love to build a proper abstraction for logging, but I don't have the
time to do so right now.
* The dataflash libs need to be pushed into the AP_HAL_AVR anyway, so I'll
do that now and replace the interface with a better logging driver later.
* BetterStream Means AP_HAL depends on AP_Common, for now, in order to have
the AVR specific pgm_char_t defined.
I'll need to factor that out in the future but for now it can stay
