New way of starting arrange and rotation optimization.

To prevent segfaults when exiting while processing is running.

src/slic3r/GUI/ProgressStatusBar.hpp

@@ -51,6 +51,7 @@ public:
     void        set_status_text(const wxString& txt);
     void        set_status_text(const std::string& txt);
     void        set_status_text(const char *txt);
+    wxString    get_status_text() const;
 
     // Temporary methods to satisfy Perl side
     void        show_cancel_button();