Performance counters: Estimate RMS for elapsed counters. Allow to use a perf counter across processes, deal with overruns and other resulting inconsistencies from cross-process use.

hmc5883: fixed handling of 3 bus options

Fixed PWM OUT command and updated flight tested params.

use a table of possible bus options. This prevents us starting two
drivers on the same bus

rcS: unset MODE and AUTOCNF

Updated submodule and config for SDIO fix

Implemented SK450 DeadCat frame support

remove/unset startup script variables

Added mixer check to set MAV_TYPE correctly

Lowered the pwm min