QmlEditor: show the id name when folding a block.

If the id of an element exists, it will be displayed instead of the normal "..."

Change-Id: I4e6633743b0e2ae014b7fbad3c752ef318c73659
Reviewed-by: Christian Kamm <christian.d.kamm@nokia.com>

src/plugins/texteditor/basetexteditor.h

@@ -507,6 +507,11 @@ protected:
 
     void maybeClearSomeExtraSelections(const QTextCursor &cursor);
 
+    /*!
+      Reimplement this function to change the default replacement text.
+      */
+    virtual QString foldReplacementText(const QTextBlock &block) const;
+
 protected slots:
     virtual void slotUpdateExtraAreaWidth();
     virtual void slotModificationChanged(bool);