REXML is dead. Long live Nokogiri.

Modify Maruku to use Nokogiri instead of REXML.
Produces a 3-fold speedup in the #to_html method.

vendor/plugins/maruku/spec/block_docs/math/inline.md

@@ -0,0 +1,46 @@
+
+*** Parameters: ***
+require 'maruku/ext/math'; {}
+*** Markdown input: ***
+Here are some formulas:
+
+*	$\alpha$
+*	$x^{n}+y^{n} \neq z^{n}$
+
+That's it, nothing else is supported.
+
+*** Output of inspect ***
+md_el(:document,[
+	md_par(["Here are some formulas:"]),
+	md_el(:ul,[
+		md_el(:li_span,[md_el(:inline_math,[],{:math=>"\\alpha"},[])],{:want_my_paragraph=>false},[]),
+		md_el(:li_span,[md_el(:inline_math,[],{:math=>"x^{n}+y^{n} \\neq z^{n}"},[])],{:want_my_paragraph=>false},[])
+	],{},[]),
+	md_par(["That", md_entity("rsquo"), "s it, nothing else is supported."])
+],{},[])
+*** Output of to_html ***
+<p>Here are some formulas:</p>
+
+<ul>
+<li><code class='maruku-mathml'>\alpha</code></li>
+
+<li><code class='maruku-mathml'>x^{n}+y^{n} \neq z^{n}</code></li>
+</ul>
+
+<p>That&#8217;s it, nothing else is supported.</p>
+*** Output of to_latex ***
+Here are some formulas:
+
+\begin{itemize}%
+\item $\alpha$
+\item $x^{n}+y^{n} \neq z^{n}$
+
+\end{itemize}
+That'{}s it, nothing else is supported.
+*** Output of to_md ***
+Here are some formulas:
+
+--
+That s it, nothing else is supported.
+*** Output of to_s ***
+Here are some formulas:Thats it, nothing else is supported.