NEW: move selected model to the center of selected plate

Change-Id: I7af49e98e83f5eef690f7d30d10a2cc240046466

src/slic3r/GUI/Plater.hpp

@@ -411,6 +411,7 @@ public:
     void paste_from_clipboard();
     //BBS: add clone logic
     void clone_selection();
+    void center_selection();
     void search(bool plater_is_active, Preset::Type  type, wxWindow *tag, wxTextCtrl *etag, wxWindow *stag);
     void mirror(Axis axis);
     void split_object();