SettingsSelector: Use Edit role when renaming

Also add a method to find the current index.

Change-Id: I54074e7050200a77d35461c4f8064c1829b5927f
Reviewed-by: Daniel Teske <daniel.teske@nokia.com>

src/libs/utils/settingsselector.h

@@ -67,6 +67,8 @@ public:
     void setAddMenu(QMenu *);
     QMenu *addMenu() const;
 
+    int currentIndex() const;
+
 signals:
     void add();
     void remove(int index);