AP_HAL: removed separate Console class

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
HAL_AVR: removed Console driver
AVR_SITL: removed Console driver
HAL_Empty: removed Console driver
HAL_FLYMAPLE: removed Console driver
HAL_Linux: removed Console driver
HAL_PX4: removed Console driver
AP_Baro: added update_calibration() method

used for auto baro calibration when disarmed
Plane: auto-update home and baro calibration when disarmed

this takes advantage of the PX4 arming state to ensure position and
baro calibration is updated