toolchain: use -O0 to get around apm blob bugs
wibble
smaccm-mavlink: regen change to smaccmpilot_nav_cmd
nav command: refactor validity boolean into enable/disable/none
mk: change general build to -O2, apm blob to -O0
control: scale heading setpoint to rads
gcs transmit driver: report yaw mode
nav: basic heading control from command to law & setpoing works!
control: heading setpoint always in radians, internally
altitude control via nav setpoint, first cut untested