fix NJointHolonomicPlatformRelativePositionController

- newTarget was not commited to write buffer

source/RobotAPI/components/units/RobotUnit/NJointControllers/NJointHolonomicPlatformRelativePositionController.cpp

@@ -61,7 +61,8 @@ namespace armarx
             startPosition = currentPosition;
             startOrientation = currentOrientation;
             pid.reset();
-            *const_cast<bool*>(&rtGetControlStruct().newTargetSet) = false;
+            getWriterControlStruct().newTargetSet = false;
+            writeControlStruct();
         }
 
         //position pid