Add option to clone favorite tools

If cloning is enabled, favorite tools will appear in the favorites panel
and in the original location.

rtgui/options.h

@@ -428,6 +428,7 @@ public:
     bool fastexport_use_fast_pipeline;
 
     std::vector<Glib::ustring> favorites;
+    bool cloneFavoriteTools;
     // Dialog settings
     Glib::ustring lastIccDir;
     Glib::ustring lastDarkframeDir;