- The global widget is a QMainWindow that includes :
        * the QtWidgetView
        * the ProgressReport Widget as a dockable widget
        * add some connections to be able to close correctly the main
          application

ENH : use more qt signals to communicate with all the pieces of the application (notification, reporting..)

      - Don't manage the progress anymore in the QtWigetView
      - Make the QtWidgetModel emitting all the signals (start reporting progress,
        reset the widgets...)
      - Create the layout once to avoid Qt warnings
      - Use the itkQtProgressBar that emit the signal relative to the ProgressEvent
        to update the ProgressBar in the application

ENH: correct compilation error, missing SetDescription method to change a parameter description from an application