Added undo/redo to the "Edit" menu

src/slic3r/GUI/Plater.cpp

@@ -4405,6 +4405,16 @@ bool Plater::can_copy_to_clipboard() const
     return true;
 }
 
+bool Plater::can_undo() const
+{
+    return p->undo_redo_stack.has_undo_snapshot();
+}
+
+bool Plater::can_redo() const
+{
+    return p->undo_redo_stack.has_redo_snapshot();
+}
+
 SuppressBackgroundProcessingUpdate::SuppressBackgroundProcessingUpdate() :
     m_was_running(wxGetApp().plater()->is_background_process_running())
 {