Apply fixes for the ui jobs.

- Localization
- Mutual exclusion (ExclusiveJobGroup), only one UI job can run at a time, and background processing is stopped
- m_range not used for finalization anymore
- stop_jobs called before Window is closed

src/slic3r/GUI/MainFrame.cpp

@@ -103,14 +103,14 @@ DPIFrame(NULL, wxID_ANY, "", wxDefaultPosition, wxDefaultSize, wxDEFAULT_FRAME_S
             event.Veto();
             return;
         }
+        
+        if(m_plater) m_plater->stop_jobs();
 
         // Weird things happen as the Paint messages are floating around the windows being destructed.
         // Avoid the Paint messages by hiding the main window.
         // Also the application closes much faster without these unnecessary screen refreshes.
         // In addition, there were some crashes due to the Paint events sent to already destructed windows.
         this->Show(false);
-        
-        if(m_plater) m_plater->stop_jobs();
 
         // Save the slic3r.ini.Usually the ini file is saved from "on idle" callback,
         // but in rare cases it may not have been called yet.