Fixed crash on startup with vtk6+qt5. All cloud viewers in QDockWidget are now created manually instead of being defined in the *.ui files. The generated ui didn't pass the top level parent window to constructor of CloudViewer, which caused a problem when initializing the QVTKWidget.

guilib/include/rtabmap/gui/MainWindow.h

@@ -52,6 +52,7 @@ class CameraOpenni;
 class CameraFreenect;
 class OdometryThread;
 class CloudViewer;
+class LoopClosureViewer;
 }
 
 class QGraphicsScene;
@@ -307,6 +308,9 @@ private:
 
 	ProgressDialog * _initProgressDialog;
 
+	CloudViewer * _cloudViewer;
+	LoopClosureViewer * _loopClosureViewer;
+
 	QString _graphSavingFileName;
 	QMap<int, QString> _exportPosesFileName;
 	bool _autoScreenCaptureOdomSync;