ENH: use a 128x128 application icon, like qt-designer

Code/Application/mvdApplication.cxx

@@ -209,8 +209,8 @@ Application
     "orfeo-toolbox.org"
   );
 
-#if ! defined(Q_WS_WIN) && ! defined(Q_WS_MAC)
-  setWindowIcon( QPixmap( monteverdi2_xpm ) );
+#ifndef Q_WS_MAC
+    setWindowIcon(QIcon(QLatin1String(":/images/application_icon")));
 #endif
 
 }

Code/Application/mvdMainWindow.qrc

-<!DOCTYPE RCC>
 <RCC>
   <qresource prefix="/icons">
     <file alias="action_Open_Icon">../../Data/Icons/document-open_32x32.png</file>
   </qresource>
+  <qresource prefix="/images">
+    <file alias="application_icon">../../Data/Icons/monteverdi2-128x128.png</file>
+  </qresource>
 </RCC>