- 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

      - Done here to tell to the qt view that the parameter has changed, the view
        ask if the application is ready to be executed, depending on the states of
        parameters, the Execute button is enabled or not