Editor: Introduce circular clipboard

This is a clipboard within Creator only. It allows the user to paste/navigate
through the recently copied content by repeatedly triggering a shortcut (which
is by default set to Ctrl+Shift+V).

Task-number: QTCREATORBUG-146
Change-Id: Ie449ab4b304548d5037a0c877bbbc0344d654325
Reviewed-by: Eike Ziller <eike.ziller@nokia.com>

src/plugins/texteditor/texteditoractionhandler.h

@@ -98,6 +98,7 @@ private slots:
     void copyAction();
     void cutAction();
     void pasteAction();
+    void circularPasteAction();
     void selectAllAction();
     void gotoAction();
     void printAction();
@@ -166,6 +167,7 @@ private:
     QAction *m_copyAction;
     QAction *m_cutAction;
     QAction *m_pasteAction;
+    QAction *m_circularPasteAction;
     QAction *m_selectAllAction;
     QAction *m_gotoAction;
     QAction *m_printAction;