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.

1998/bas2/index.html

@@ -141,16 +141,16 @@ Location: <a href="../../location.html#NL">NL</a> - <em>Kingdom of the Netherlan
 <!-- 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> all</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    make all</code></pre>
 <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">./bas2</span> <span class="op">&lt;</span> file</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">echo</span> text <span class="kw">|</span> <span class="ex">./bas2</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./bas2 &lt; file
+    echo text | ./bas2</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>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb3-3"><a href="#cb3-3" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./try.sh</span> <span class="st">&quot;foo bar&quot;</span> <span class="st">&quot;baz&quot;</span> <span class="st">&quot;IOCCC 1998/bas2&quot;</span> README.md</span>
-<span id="cb3-4"><a href="#cb3-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb3-5"><a href="#cb3-5" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./try.sh</span> try.sh <span class="st">&quot;bas2.c&quot;</span> bas2.orig.c</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./try.sh
+
+    ./try.sh &quot;foo bar&quot; &quot;baz&quot; &quot;IOCCC 1998/bas2&quot; README.md
+
+    ./try.sh try.sh &quot;bas2.c&quot; bas2.orig.c</code></pre>
 <h2 id="judges-remarks">Judges’ remarks:</h2>
 <h3 id="questions-to-ponder">Questions to ponder:</h3>
 <p>Can you determine the relationship between the input and the resulting numeric