title: get all nodes and its content using htmldocument/HtmlAgilityPack
body: <p>I need to get all nodes from a html, then from that nodes I need to get the text and sub-nodes, and the same thing but from that sub-sub-nodes.
  For example, I have this HTML:</p>
  
  <pre><code>&lt;p&gt;This &lt;b&gt;is a &lt;a href=""&gt;Link&lt;/a&gt;&lt;/b&gt; with &lt;b&gt;bold&lt;/b&gt;&lt;/p&gt;
  </code></pre>
  
  <p>So I need a way to get the <strong>p</strong> node, then the non-formatted text (this), the only-bold text (<strong>is a</strong>), the bolded link (<strong><a href="http://www.google.com/" rel="nofollow noreferrer">Link</a></strong>) and the rest formatted and not formatted text.</p>
  
  <p>I know that with the htmldocument I can select all nodes and sub-nodes, but, how Can I get the text before the sub-node, then the sub-node, and its text/sub-nodes so I can make the rendered version of the html ("This <strong>is a <a href="http://www.google.com/" rel="nofollow noreferrer">Link</a></strong> with <strong>bold</strong>")?</p>
  
  <p>Please note that the above example is a simple one. The HTML would have more complex things like list, frames, numbered list, triple-formatted text, etc. Also note that the rendered thing is not a problem. I have already done that but in another way. What I need is the part to get the nodes and its content only.
  Also, I can't ignore any node, so I can't filter by nothing. And the main node could start as p, div, frame, ul, etc.</p>