supports url's as destination of toc items

(although i have no djvu documents with such stuff, so i could not test it properly)

svn path=/trunk/KDE/kdegraphics/okular/; revision=890903

generators/djvu/generator_djvu.cpp

@@ -47,6 +47,10 @@ static void recurseCreateTOC( QDomDocument &maindoc, const QDomNode &parent, QDo
             vp.pageNumber = dest.toInt() - 1;
             newel.setAttribute( "Viewport", vp.toString() );
         }
+        else if ( !( dest = el.attribute( "URL" ) ).isEmpty() )
+        {
+            newel.setAttribute( "URL", dest );
+        }
 
         if ( el.hasChildNodes() )
         {