0031570: Samples - add Qt samples similar to standard MFC samples

Added Qt sample OCCTOverview providing examples of use of OCCT API with relevant code and demonstration of results in the viewer.

Off-topic: some unused images are removed from dox/introduction/images/

samples/qt/OCCTOverview/src/GeomWidget.h

@@ -0,0 +1,65 @@
+// Copyright (c) 2020 OPEN CASCADE SAS
+//
+// This file is part of the examples of the Open CASCADE Technology software library.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE
+
+#ifndef GEOMWIDGET_H
+#define GEOMWIDGET_H
+
+#include "View.h"
+#include "DocumentCommon.h"
+
+#include <Standard_WarningsDisable.hxx>
+#include <QWidget>
+#include <Standard_WarningsRestore.hxx>
+
+class ApplicationCommon;
+class QStackedWidget;
+
+//! Qt widget for organize 3D & 2D documents
+class GeomWidget : public QWidget
+{
+  Q_OBJECT
+public:
+  GeomWidget(DocumentCommon* theDocument3d,
+             DocumentCommon* theDocument2d,
+             QWidget* theParent = nullptr);
+
+  void FitAll();
+
+  Handle(V3d_View) Get3dView() { return myView3d->getView(); }
+
+  Handle(V3d_View) Get2dView() { return myView2d->getView(); }
+
+  void Show3d();
+  void Show2d();
+
+private:
+  View*    myView3d;
+  View*    myView2d;
+
+  QWidget* my3dVidget;
+  QWidget* my2dVidget;
+  QStackedWidget* myStackWidget;
+
+  DocumentCommon* myDocument3d;
+  DocumentCommon* myDocument2d;
+};
+
+#endif //GEOMWIDGET_H