Add vehicle_angular_acceleration topic and sensor

msg/CMakeLists.txt

@@ -130,6 +130,7 @@ set(msg_files
 	ulog_stream_ack.msg
 	vehicle_acceleration.msg
 	vehicle_air_data.msg
+	vehicle_angular_acceleration.msg
 	vehicle_angular_velocity.msg
 	vehicle_attitude.msg
 	vehicle_attitude_setpoint.msg

msg/vehicle_angular_acceleration.msg

@@ -0,0 +1,7 @@
+
+uint64 timestamp	# time since system start (microseconds)
+uint64 timestamp_sample # timestamp of the data sample on which this message is based (microseconds)
+
+float32[3] xyz		# angular acceleration about X, Y, Z body axis in rad/s^2,
+			# computed by differentiating vehicle_angular_velocity and applying a low pass filter
+			# can be used to verify that the vehicle correctly tracks angular acceleration setpoints