airframes srcparser.py: Allow non-param comments
airframes srcparser.py: Allow non-param comments

Add a "@desc" tag that gets ignored by the parameter parser.  This
allows you to add (multi-line) documentation to airframe init files.

acfloria/Firmware,PX4/Firmware,PX4/Firmware,PX4/Firmware,acfloria/Firmware,PX4/Firmware,krbeverx/Firmware,PX4/Firmware,acfloria/Firmware,krbeverx/Firmware,krbeverx/Firmware,krbeverx/Firmware,krbeverx/Firmware,acfloria/Firmware,PX4/Firmware,krbeverx/Firmware,acfloria/Firmware,krbeverx/Firmware,PX4/Firmware,acfloria/Firmware,acfloria/Firmware