ardupilotmega: added RALLY_POINT and RALLY_FETCH point msg defs.

Rally points will be used to allow the plan to RTL to locations
other than the Home location.
mavwp: Added a rally point loader.

This will be used in MAVProxy to allow loading rally points.
ardupilotmega: added FENCE_ACTION_GUIDED_THR_PASS

this is for guided mode with throttle pass-thru
pymavlink: raise version for release
ardupilotmega: added MAV_CMD_DO_SET_CAM_TRIGG_DIST