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/math/notmath.md

@@ -0,0 +1,40 @@
+
+*** Parameters: ***
+require 'maruku/ext/math'; {:math_enabled => false}
+*** Markdown input: ***
+
+This is not $math$.
+
+\[ \alpha \]
+
+*** Output of inspect ***
+md_el(:document,[md_par(["This is not $math$."]), md_par(["[ \\alpha ]"])],{},[])
+*** Output of to_html ***
+<p>This is not $math$.</p>
+
+<p>[ \alpha ]</p>
+*** Output of to_latex ***
+This is not \$math\$.
+
+[ $\backslash$alpha ]
+*** Output of to_md ***
+This is not $math$.
+
+[ \alpha ]
+*** Output of to_s ***
+This is not $math$.[ \alpha ]
+*** EOF ***
+
+
+
+	OK!
+
+
+
+*** Output of Markdown.pl ***
+<p>This is not $math$.</p>
+
+<p>[ \alpha ]</p>
+
+*** Output of Markdown.pl (parsed) ***
+Error: #<NoMethodError: private method `write_children' called for <div> ... </>:REXML::Element>