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.

2018/anderson/index.html

@@ -141,29 +141,29 @@ Location: <a href="../../location.html#US">US</a> - <em>United States of America
 <!-- 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 alternate version of this entry. See <a href="#alternate-code">Alternate
 code</a> below for more 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> textfile</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./prog &lt; textfile</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>Compare <a href="prog.c">prog.c</a> and <a href="prog.alt.c">prog.alt.c</a> and find out why we had to
 modify the entry, and what confused the author (see the author’s remarks). No,
 it was not the shape of the Roman V that we, or the compiler, didn’t like.</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>
 <h3 id="alternate-try">Alternate try:</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">./try.alt.sh</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./try.alt.sh</code></pre>
 <h2 id="judges-remarks">Judges’ remarks:</h2>
 <p>With this entry, you won’t need to turn your monitor <a href="http://en.wikipedia.org/wiki/River_%28typography%29">upside
 down</a>!</p>
 <h2 id="authors-remarks">Author’s remarks:</h2>
 <h3 id="compiling-the-program">Compiling the program:</h3>
-<div class="sourceCode" id="cb6"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a>    <span class="fu">cc</span> <span class="at">-Wall</span> <span class="at">-Wextra</span> <span class="at">-Wpedantic</span> <span class="at">-O3</span> <span class="at">-std</span><span class="op">=</span>c11 prog.c <span class="at">-o</span> prog</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    cc -Wall -Wextra -Wpedantic -O3 -std=c11 prog.c -o prog</code></pre>
 <p>Also works with a standard of C99, but C90/C89 will not compile due to
 <code>for</code> loop initial declarations, along with additional warnings about
 variable length arrays and lack of a <code>return</code> statement.</p>