check correctly tandem.exe returned code on exit

src/core/tandem_run/tandembatchprocess.cpp

src/core/tandem_run/tandemcondorprocess.cpp

src/core/tandem_run/tandemparameters.h

src/core/tandem_run/tandemrunbatch.h

src/gui/mainwindow.cpp

src/gui/mainwindow.h

src/gui/waiting_message_dialog/waitingmessagedialog.cpp

src/gui/waiting_message_dialog/waitingmessagedialog.h

src/gui/workerthread.cpp

src/utils/workmonitor.cpp

src/utils/workmonitor.h