Added a few modifications concerning the behavior of the mitkUSIGTLDevice.cpp if OnConnection() or OnActivation() is called by the USDevice class. It seems that in case of an USIGTLDevice the OpenIGTLink-connection already exists and mustn't be restarted again when the combined modality starts its calibration process. Now using the OpenIGTLink-connection for displaying the US-image in combination with the combined modality is possible now. Further tests with hardware have to be made.