added missing base class in sensor value class

source/RobotAPI/components/units/RobotUnit/SensorValues/SensorValue1DoFActuator.h

@@ -119,6 +119,7 @@ namespace armarx
             svi.addBaseClass<SensorValue1DoFActuatorVelocity>();
             svi.addBaseClass<SensorValue1DoFActuatorAcceleration>();
             svi.addBaseClass<SensorValue1DoFActuatorTorque>();
+            svi.addBaseClass<SensorValue1DoFGravityTorque>();
             return svi;
         }
     };