[apps/settings] Implement setting menu with a tree (for navigation)

Change-Id: Ie27c3c25085a279c47eb53f3f1054d970b607f8b

apps/settings/settings_node.cpp

@@ -0,0 +1,9 @@
+#include "settings_node.h"
+
+namespace Settings {
+
+const Node * SettingsNode::children(int index) const {
+  return &m_children[index];
+}
+
+}