mvvm: standard file header comment blocks

gui2/core/app_constants.h

gui2/core/version.h

gui2/dataloader/datahandler.cpp

gui2/dataloader/datahandler.h

gui2/dataloader/dataloader_constants.h

gui2/dataloader/dataloader_types.h

gui2/dataloader/dataloader_utils.cpp

gui2/dataloader/dataloader_utils.h

gui2/dataloader/dataloaderdialog.cpp

gui2/dataloader/dataloaderdialog.h

gui2/dataloader/dataloadertoolbar.cpp

gui2/dataloader/dataloadertoolbar.h

gui2/dataloader/defaultparser.cpp

gui2/dataloader/defaultparser.h

gui2/dataloader/importfilewidget.cpp

gui2/dataloader/importfilewidget.h

gui2/dataloader/importtableheader.cpp

gui2/dataloader/importtableheader.h

gui2/dataloader/importtablemodel.cpp

gui2/dataloader/importtablemodel.h