add hack-a-round for language specified markdown code blocks

When language is specified in a markdown code block such as:

````
```c
    printf("Hello, world!\n");
```
````

is used, the resulting HTML as produced by `pandoc(1)` combined
with our revised `ioccc.css` is not intent the code block well.

A temporary "_hack-a-round_" is to turn the "markdown code language
specifier" into an HTML comment.  For example:

````
```<!---c-->
    printf("Hello, world!\n");
```
````

This commits turns off existing markdown code language specifiers
for now, while preserving our ability to restore them in the future
when a better  "_hack-a-round_" to the "markdown code language
specifier" problem is found.

The HTML impact if this "_hack-a-round_" is to produce HTML that
looks like this:

```
<pre class="&lt;!---c--&gt;"><code> .. </code></pre>
```

We might be able to create a complex set of classes for each markdown
code language (there won't be very many) in `ioccc.css`, or we might
find a more general CSS (or maybe `pandoc(1)`?) solution.

For now, this hack-a-round will have to do.

2015/endoh4/index.html

@@ -141,19 +141,19 @@ Location: <a href="../../location.html#JP">JP</a> - <em>Japan</em></li>
 <!-- START: this line starts content for HTML phase 21 by: bin/pandoc-wrapper.sh via bin/md2html.sh -->
 
 <h2 id="to-build">To build:</h2>
-<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>    <span class="fu">make</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    make</code></pre>
 <p>There is an alt version which is the originally submitted entry. See <a href="#alternate-code">Alternate
 code</a> below for details.</p>
 <h2 id="to-use">To use:</h2>
-<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./prog</span> <span class="op">&lt;</span>a number of arguments<span class="op">&gt;</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./prog &lt;a number of arguments&gt;</code></pre>
 <h2 id="try">Try:</h2>
-<div class="sourceCode" id="cb3"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./try.sh</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./try.sh</code></pre>
 <h2 id="alternate-code">Alternate code:</h2>
 <p>An alternate version of this entry, <a href="prog.alt.c">prog.alt.c</a>, is provided.
 This alternate code does not contain improvements suggested by <a href="../../authors.html#Gil_Dogon">Gil
 Dogon</a>; it is the author’s original entry.</p>
 <h3 id="alternate-build">Alternate build:</h3>
-<div class="sourceCode" id="cb4"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a>    <span class="fu">make</span> alt</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    make alt</code></pre>
 <h3 id="alternate-use">Alternate use:</h3>
 <p>Use <code>prog.alt</code> as you would <code>prog</code> above.</p>
 <h2 id="judges-remarks">Judges’ remarks:</h2>
@@ -163,14 +163,14 @@ run out of command line argument space? How could you modify the program to
 experiment with numbers that have more or larger factors?</p>
 <h2 id="authors-remarks">Author’s remarks:</h2>
 <p>Visual factorization 1-liner. Try:</p>
-<div class="sourceCode" id="cb5"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>    <span class="fu">gcc</span> <span class="at">-o</span> prog prog.c</span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./prog</span> @</span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./prog</span> @ @</span>
-<span id="cb5-4"><a href="#cb5-4" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./prog</span> @ @ @</span>
-<span id="cb5-5"><a href="#cb5-5" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./prog</span> @ @ @ @</span>
-<span id="cb5-6"><a href="#cb5-6" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./prog</span> @ @ @ @ @ @</span>
-<span id="cb5-7"><a href="#cb5-7" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./prog</span> @ @ @ @ @ @ @ @</span>
-<span id="cb5-8"><a href="#cb5-8" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./prog</span> @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    gcc -o prog prog.c
+    ./prog @
+    ./prog @ @
+    ./prog @ @ @
+    ./prog @ @ @ @
+    ./prog @ @ @ @ @ @
+    ./prog @ @ @ @ @ @ @ @
+    ./prog @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ @</code></pre>
 <p>Inspired by <a href="http://www.datapointed.net/visualizations/math/factorization/animated-diagrams/">Animated Factorization
 Diagrams</a>.</p>
 <p><a href="prog.alt.c">prog.alt.c</a> is the original version that I submitted. <a href="../../authors.html#Gil_Dogon">Gil