Signed-off-by: Roman <bapstroman@gmail.com>

If not in air-mode the mixer is not able to apply positive boosting
and roll_pitch_scale is recomputed to apply symmetric - reduced - thrust.
This has the consequence to cut completely the outputs when the thrust is
set to zero.

this avoids calling param_get() on every loop iteration.

Added in 262d9c79.

- fmu: in case of _mot_t_max==0 _airmode was not set in the mixer
- px4io: param_val is a float

* Adding pwm_out_sim
* pwm_out_sim driver will be by default part of Aero FC PX4 Nuttx drivers
* tap_esc is off when SYS_HITL 1

Fixes a mavlink 2 parsing bug

GCC error:
error: 'memcpy' was not declared in this scope

Also change naming convention: add _ prefix to class attributes