Rewrite the shortcut settings filtering.

Makes more sense now, is more generic (regarding nesting level), and
even is shorter.

Change-Id: I77ce34aa25655f6b2690964107f4cab018e1d66f
Reviewed-by: Robert Löhning <robert.loehning@nokia.com>
Reviewed-by: Eike Ziller <eike.ziller@nokia.com>

src/plugins/coreplugin/actionmanager/commandmappings.h

@@ -68,7 +68,7 @@ protected:
     virtual void finish();
 
     virtual void initialize() = 0;
-    bool filter(const QString &f, const QTreeWidgetItem *item);
+    bool filter(const QString &filterString, QTreeWidgetItem *item);
 
     // access to m_page
     void setImportExportEnabled(bool enabled);