msg: add external vision data for ekf2 replay

msg/ekf2_replay.msg

@@ -7,6 +7,7 @@ uint64 baro_timestamp			# timestamp of barometer measurement in us
 uint64 rng_timestamp			# timestamp of range finder measurement in us
 uint64 flow_timestamp			# timestamp of optical flow measurement in us
 uint64 asp_timestamp			# timestamp of airspeed measurement in us
+uint64 ev_timestamp			# timestamp of external vision measurement in us
 
 float32[3] gyro_integral_rad		# integrated gyro vector in rad
 float32[3] accelerometer_integral_m_s  	# integrated accelerometer vector in m/s
@@ -46,3 +47,8 @@ float32 true_airspeed_unfiltered_m_s	# true airspeed in meters per second, -1 if
 float32 air_temperature_celsius		# air temperature in degrees celsius, -1000 if unknown
 float32 confidence			# confidence value from 0 to 1 for this sensor
 
+# external vision measurements
+float32[3] pos_ev			# position in earth (NED) frame (metres)
+float32[4] quat_ev			# quaternion rotation from earth (NED) to body (XYZ) frame
+float32 pos_err				# position error 1-std for each axis (metres)
+float32 ang_err				# angular error 1-std for each axis (rad)