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/dloweneil/index.html

@@ -144,7 +144,7 @@ Location: <a href="../../location.html#ZZ">ZZ</a> - <em>Unknown location</em></l
 <!-- 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>
 <p>There is an alternate version available that has a key configuration that will
 be more familiar to vi(m) users and also allows one to quit. See <a href="#alternate-code">alternate
 code</a> below.</p>
@@ -153,7 +153,7 @@ code</a> below.</p>
 <pre><code>    STATUS: missing or dead link - please provide them</code></pre>
 <p>For more detailed information see <a href="../../bugs.html#1998_dloweneil">1998 dloweneil bugs</a>.</p>
 <h2 id="to-use">To use:</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">./pootris</span> [X size of board] [Y size of board]</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./pootris [X size of board] [Y size of board]</code></pre>
 <p>Pressing <code>a</code> moves the current letter position counterclockwise/anticlockwise
 (a)round the border of the playing field.</p>
 <p>Pressing <code>s</code> moves the current letter one position clockwise around the border
@@ -165,9 +165,9 @@ counterclockwise/anticlockwise <code>h</code> does as well; and in addition to <
 clockwise <code>l</code> does as well. Instead of using <code>d</code> to drop the letter you can do
 <code>j</code> or space. Finally to quit this version you can press <code>q</code>.</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>
-<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="ex">./pootris.alt</span> [X size of board] [Y size of board]</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./pootris.alt [X size of board] [Y size of board]</code></pre>
 <h2 id="judges-remarks">Judges’ remarks:</h2>
 <p>Read the authors’ remarks below to find out how to play. We believe that your
 experience may mirror one of our experiences:</p>
@@ -176,7 +176,7 @@ experience may mirror one of our experiences:</p>
     I spelled my first &quot;poot&quot;.  I was hooked ...</code></pre>
 <h2 id="authors-remarks">Author’s remarks:</h2>
 <h3 id="usage">Usage</h3>
-<div class="sourceCode" id="cb7"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./pootris</span> [X size of board] [Y size of board]</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./pootris [X size of board] [Y size of board]</code></pre>
 <h3 id="synopsis">Synopsis</h3>
 <p>The object of this game is to spell <code>POOT</code> as much as possible. There
 is no time pressure. You’re given one letter at a time (sort of randomly