Copter: STB_RLL_P and STB_PIT_P @Range 3 to 12
RC_Channel: added support for LimitValue settings

this allows you to set a channel failsafe or radio_out to a limit
value
APM_OBC: setup termination values in PX4IO

this sets up the PX4IO board with failsafe values in case the FMU is
not running
Plane: use new APM_OBC API
Plane: setup failsafe values for OBC in failsafe callback
Replay: added -A option to set arming time
AP_NavEKF: fixed millisecond subtraction for rollover

Pair-Programmed-With: Paul Riseborough <p_riseborough@live.com.au>
PosControl: update_pos_controller renamed to update_xy_controller
Circle: integrate update_xy_controller name change
AC_WPNav: integrate update_xy_controller name change
Copter: set main loop rate from CPU class

Previously this was determined by the board
AC_WPNav: run loiter and wp nav at 50hz on Pixhawk
Replay: added floating point exception checking

allows NaN errors to be caught in gdb
AP_AHRS: prevent a infinity value
AP_Math: prevent a floating point exception
AP_NavEKF: catch covarience errors and reset filter

this catches covariance values beyond a reasonable limit and resets
the filter is they happen
SITL: added SIM_FLOAT_EXCEPT parameter

this enables checking for floating point exceptions
HAL_SITL: enable use of SIM_FLOAT_EXCEPT parameter
AC_WPNav: update target speed immediately
AC_WPNav: rename some definitions