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/code3.md

@@ -0,0 +1,71 @@
+Write a comment abouth the test here.
+*** Parameters: ***
+{}
+*** Markdown input: ***
+
+This is code (4 spaces):
+
+    Code
+This is not code
+    
+    Code
+
+This is code (1 tab):
+
+	Code
+This is not code
+
+	Code
+
+
+
+*** Output of inspect ***
+md_el(:document,[
+	md_par(["This is code (4 spaces):"]),
+	md_el(:code,[],{:raw_code=>"Code"},[]),
+	md_par(["This is not code"]),
+	md_el(:code,[],{:raw_code=>"Code"},[]),
+	md_par(["This is code (1 tab):"]),
+	md_el(:code,[],{:raw_code=>"Code"},[]),
+	md_par(["This is not code"]),
+	md_el(:code,[],{:raw_code=>"Code"},[])
+],{},[])
+*** Output of to_html ***
+<p>This is code (4 spaces):</p>
+
+<pre><code>Code</code></pre>
+
+<p>This is not code</p>
+
+<pre><code>Code</code></pre>
+
+<p>This is code (1 tab):</p>
+
+<pre><code>Code</code></pre>
+
+<p>This is not code</p>
+
+<pre><code>Code</code></pre>
+*** Output of to_latex ***
+This is code (4 spaces):
+
+\begin{verbatim}Code\end{verbatim}
+This is not code
+
+\begin{verbatim}Code\end{verbatim}
+This is code (1 tab):
+
+\begin{verbatim}Code\end{verbatim}
+This is not code
+
+\begin{verbatim}Code\end{verbatim}
+*** Output of to_md ***
+This is code (4 spaces):
+
+This is not code
+
+This is code (1 tab):
+
+This is not code
+*** Output of to_s ***
+This is code (4 spaces):This is not codeThis is code (1 tab):This is not code