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/test.md

@@ -0,0 +1,32 @@
+Write a comment abouth the test here.
+*** Parameters: ***
+{}
+*** Markdown input: ***
+
+           $ python       
+
+
+
+*** Output of inspect ***
+md_el(:document,[md_el(:code,[],{:raw_code=>"       $ python       "},[])],{},[])
+*** Output of to_html ***
+<pre><code>       $ python       </code></pre>
+*** Output of to_latex ***
+\begin{verbatim}       $ python       \end{verbatim}
+*** Output of to_md ***
+
+*** Output of to_s ***
+
+*** EOF ***
+
+
+
+	OK!
+
+
+
+*** Output of Markdown.pl ***
+<p>$ python       </p>
+
+*** Output of Markdown.pl (parsed) ***
+Error: #<NoMethodError: private method `write_children' called for <div> ... </>:REXML::Element>