minor refactor

Arrangement_on_surface_2/demo/earth/Aos.cpp

@@ -1090,8 +1090,8 @@ void Aos::save_arr(Kml::Placemarks& placemarks, const std::string& file_name)
   }
   std::cout << "total num half-edges = " << total_num_half_edges << std::endl;
  
-  std::ofstream ofile("C:/work/gsoc2023/deneme.txt");
-  ofile << js;
+  // save the arrangment
+  std::ofstream ofile(file_name);
+  ofile << js.dump(2);
   ofile.close();
-
-}
+}

Arrangement_on_surface_2/demo/earth/Main_widget.cpp

@@ -218,7 +218,7 @@ void Main_widget::initializeGL()
   }
 
   {
-    Aos::save_arr(m_countries, "");
+    Aos::save_arr(m_countries, "C:/work/gsoc2023/deneme.json");
   }
   
   // initialize rendering of DUPLICATE VERTICES