Update to latest HTML5lib, Add Maruku testdir

Sync with the latest html5lib.
Having the Maruku unit tests on-hand may be useful for debugging; so let's include them.

vendor/plugins/maruku/tests/unittest/code2.md

@@ -0,0 +1,46 @@
+Write a comment abouth the test here.
+*** Parameters: ***
+{}
+*** Markdown input: ***
+> Code
+>
+>     Ciao
+*** Output of inspect ***
+md_el(:document,[
+	md_el(:quote,[md_par(["Code"]), md_el(:code,[],{:raw_code=>"Ciao"},[])],{},[])
+],{},[])
+*** Output of to_html ***
+<blockquote>
+<p>Code</p>
+
+<pre><code>Ciao</code></pre>
+</blockquote>
+*** Output of to_latex ***
+\begin{quote}%
+Code
+
+\begin{verbatim}Ciao\end{verbatim}
+
+\end{quote}
+*** Output of to_md ***
+Code
+*** Output of to_s ***
+Code
+*** EOF ***
+
+
+
+	OK!
+
+
+
+*** Output of Markdown.pl ***
+<blockquote>
+  <p>Code</p>
+
+<pre><code>Ciao
+</code></pre>
+</blockquote>
+
+*** Output of Markdown.pl (parsed) ***
+Error: #<NoMethodError: private method `write_children' called for <div> ... </>:REXML::Element>