Monteverdi black screen after app execution

Merge request linked with issue #1588 (closed)

After an application execution, if an output image has been created, the new image data is imported in Monteverdi, but there is no call to the ImageViewWidget's (inheriting from QGLWidget) UpdateGL() method and therefore the data is not displayed until the next UpdateGL call (mouse click, scroll, image opened ...).

This merge request adds a call to this method after app execution if an output image has been created.