0027398: Integrate Qt Browser Widget to Open CASCADE Technology

The following implementation has been made:
- CMake procedure is extended to compile Qt tools. This is optional and is handled by USE_QT_TOOLS option(OFF by default)
- It is possible to build Qt tools using Qt5 or Qt4, it is settled with USE_QT4 option.
- Sample of DFBrowser tool is available in samples/tools/TInspectorEXE. It is build with tools, executable is placed in binaries. To start the sample, use dfbrowser.bat command.
- DFBrowser tool may be started from DRAW

tools/DFBrowserPane/DFBrowserPane_ItemDelegateButton.cxx

@@ -0,0 +1,54 @@
+// Created on: 2017-06-16
+// Created by: Natalia ERMOLAEVA
+// Copyright (c) 2017 OPEN CASCADE SAS
+//
+// This file is part of Open CASCADE Technology software library.
+//
+// This library is free software; you can redistribute it and/or modify it under
+// the terms of the GNU Lesser General Public License version 2.1 as published
+// by the Free Software Foundation, with special exception defined in the file
+// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
+// distribution for complete text of the license and disclaimer of any warranty.
+//
+// Alternatively, this file may be used under the terms of Open CASCADE
+// commercial license or contractual agreement. 
+
+#include <DFBrowserPane_ItemDelegateButton.hxx>
+
+#include <QAbstractItemModel>
+#include <QEvent>
+#include <QPainter>
+
+// =======================================================================
+// function : Constructor
+// purpose :
+// =======================================================================
+DFBrowserPane_ItemDelegateButton::DFBrowserPane_ItemDelegateButton (QObject* theParent, const QString& theIcon)
+: QStyledItemDelegate (theParent)
+{
+  myIcon = QIcon (theIcon);
+}
+
+// =======================================================================
+// function : paint
+// purpose :
+// =======================================================================
+void DFBrowserPane_ItemDelegateButton::paint (QPainter* thePainter, const QStyleOptionViewItem& theOption,
+                                              const QModelIndex& theIndex) const
+{
+  if (!myFreeRows.contains (theIndex.row()))
+    thePainter->drawPixmap (theOption.rect, myIcon.pixmap (20,20));
+}
+
+// =======================================================================
+// function : editorEvent
+// purpose :
+// =======================================================================
+bool DFBrowserPane_ItemDelegateButton::editorEvent (QEvent* theEvent, QAbstractItemModel* theModel,
+                                                    const QStyleOptionViewItem& theOption, const QModelIndex& theIndex)
+{
+  if (theEvent->type() == QEvent::MouseButtonPress && !myFreeRows.contains (theIndex.row()))
+    emit buttonPressed (theIndex);
+
+  return QStyledItemDelegate::editorEvent (theEvent, theModel, theOption, theIndex);
+}