Plane: move delay callback setup to after compass and airspeed config

this ensure parameters sent on startup include compass settings and
airspeed offset
Plane: fixed number of channels we pass to PWM limits
Plane: fixed potential division by zero in mixing creation

also setup failsafe values if already armed, so while loading new
mixer the throttle output doesn't go to zero
Plane: update OVERRIDE_CHAN docs
Plane: change default autotune level to 6
AP_HAL_AVR_SITL: fill in ublox accuracy metrics with reasonable values
AP_Notify:Add ToneAlarm Support for HAL_Linux Boards
HAL_Linux: Add ToneAlarm Driver to Linux_HAL

ToneAlarm is setup for Beaglebone Black using pwm, toneAlarm thread runs on second last priority.
AP_HAL: Add virtual toneAlarm member functions to be declared under Linux_HAL
Tools/Linux_HAL_Essentials: Add loading of PWM capes to support ToneAlarm

new capes to be loaded by startup.sh: am33xx_pwm and bone_pwm_P8_36
HAL_Linux: change the return type of AP_HAL::Util::tonealarm_init() to signed int8_t.
This is a part of a set of fixes for the bugs and typos tridge discovered and shared inside earlier commits for setting up tonealarm.
AP_Notify:Fix the typo, usage of toshibaled.init() instead of toshibaled.update()
This is a part of a set of fixes for the bugs and typos tridge discovered and shared inside earlier commits for setting up tonealarm.
AP_Notify:change tonealarm-type bitmask to bool type,
change parameter data type from const uint8_t to uint8_t,
initialise tonealarm error flag to value -1 at tonealarm class initiallisation

This is a part of a set of fixes for the bugs and typos tridge discovered and shared inside earlier commits for setting up tonealarm.
AP_Notify: fixed bitfields
HAL_Linux: use dprintf() instead of sprintf and write
Plane: prevent large G_Dt_max report on startup
AP_Param: check parameter tables for bad suffix lengths
AP_RangeFinder: fixed oversized parameter RNGFND2_SETTLE_MS
BaroGlitch: add reset method
Copter: reset baro glitch after baro init