Still need to handle switches for 2.0 board in hal.
Should probably move into hal ctor.

Also improved documentation of AP_ControllerBlock.

Currently APO quad/plane/tank need to be updated
for new controller changes.

Still need to add arming/ disarming to rover/boat controllers.

Arming added for quadrotor. Need to add to rover still. Battery
monitoring added with auto shut-off in quadrotor controller.
Finally split apo header and source files to allow faster
compiling/ fix cyclic header inclusions.

Needs more gain tuning.

ArduPlane/ ArduCopter should be easy to convert. The only thing
left for cmake is sketch processing, upstream dev is workign on this
at github, see arduino-cmake project.