added relay module

used to control servos and relays
HIL: setup for new HIL plane code
release 1.2.6
Moved rally control out of mayproxy.py into its own module.
prevent a disconnected serial port from causing the CPU to spin
mavproxy_rally.py: fixed up comments to conform to pydoc
lower CPU load when idle
rcsetup: Replaced rcreset cmd with rccal for safer radio calibration.
rcsetup: Added warning message for electric motors.
rcsetup: Usage stmt printed for rccal when invalid args given.
mavproxy: Tab completion added.
rline: move readline handling into its own library
rline: removed debug code
print full backtrace on failed module load with moddebug > 1
added compassmot command
added --rtscts option
fence: moved fence into its own module
console: report POWER_STATUS flags