lib: Remove `NodeRenderer'

`NodeRenderer' is superseded by `TocRenderer'.

library/Icinga/Data/Tree/NodeRenderer.php

@@ -1,58 +0,0 @@
-<?php
-// {{{ICINGA_LICENSE_HEADER}}}
-// {{{ICINGA_LICENSE_HEADER}}
-
-namespace Icinga\Data\Tree;
-
-use Exception;
-use RecursiveIteratorIterator;
-use RuntimeException;
-
-/**
- * A not yet customizable node renderer
- */
-class NodeRenderer extends RecursiveIteratorIterator
-{
-    protected $content = array();
-
-    public function __construct(NodeInterface $node)
-    {
-        parent::__construct($node, RecursiveIteratorIterator::SELF_FIRST);
-    }
-
-    public function beginIteration()
-    {
-        $this->content[] = '<ul>';
-    }
-
-    public function endIteration()
-    {
-        $this->content[] = '</ul>';
-    }
-
-    public function beginChildren()
-    {
-        $this->content[] = '<ul>';
-    }
-
-    public function endChildren()
-    {
-        $this->content[] = '</ul>';
-    }
-
-    public function render($callback)
-    {
-        if (! is_callable($callback)) {
-            throw new RuntimeException('Callable expected');
-        }
-        foreach ($this as $node) {
-            try {
-                $content = call_user_func($callback, $node);
-            } catch (Exception $e) {
-                throw new RuntimeException($e);
-            }
-            $this->content[] = $content;
-        }
-        return implode("\n", $this->content);
-    }
-}