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/math_usage/math.css

@@ -0,0 +1,26 @@
+
+body {
+	max-width: 35em;
+}
+
+span.maruku-inline .maruku-mathml  {
+	//display: none;
+}
+
+div.maruku-equation .maruku-mathml  {
+	//display: none;
+}
+
+span.maruku-inline .maruku-png  {
+}
+
+div.maruku-equation .maruku-png  {
+}
+
+div.maruku-equation {
+	text-align: center;
+}
+
+div.maruku-equation span.maruku-eq-number  {
+	display: block; float: right; padding-right: 2em;
+}