FlightModeManager: Add task for position slow mode

msg/CMakeLists.txt

@@ -234,6 +234,7 @@ set(msg_files
 	VehicleTorqueSetpoint.msg
 	VehicleTrajectoryBezier.msg
 	VehicleTrajectoryWaypoint.msg
+	VelocityLimits.msg
 	VtolVehicleStatus.msg
 	WheelEncoders.msg
 	Wind.msg

msg/VelocityLimits.msg

@@ -0,0 +1,8 @@
+# Velocity and yaw rate limits for a multicopter position slow mode only
+
+uint64 timestamp # time since system start (microseconds)
+
+# absolute speeds, NAN means use default limit
+float32 horizontal_velocity # [m/s]
+float32 vertical_velocity # [m/s]
+float32 yaw_rate # [rad/s]