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.

2004/schnitzi/README.md

@@ -1,20 +1,20 @@
 ## To build:
 
-```sh
+```<!---sh-->
     make
 ```
 
 
 ## To use:
 
-```sh
+```<!---sh-->
     ./schnitzi <foo | vi -n
 ```
 
 
 ## Try:
 
-```sh
+```<!---sh-->
     ./try.sh
 ```
 
@@ -132,13 +132,13 @@ Try one of these methods to get the animation to run:
 
 1.  Redirect the output directly to vi, like this:
 
-```sh
+```<!---sh-->
     ./schnitzi < input.dat | vi
 ```
 
 2.  Redirect the output to a file, like this:
 
-```sh
+```<!---sh-->
     ./schnitzi < input.dat > output.dat
 ```
 

2004/schnitzi/index.html

@@ -141,11 +141,11 @@ 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></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    make</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">./schnitzi</span> <span class="op">&lt;</span>foo <span class="kw">|</span> <span class="fu">vi</span> <span class="at">-n</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./schnitzi &lt;foo | vi -n</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>
 <p>NOTE: if you’re one of those who don’t know how to exit <code>vi</code> :-) don’t worry as
 it will exit for you.</p>
 <h2 id="judges-remarks">Judges’ remarks:</h2>
@@ -221,11 +221,11 @@ scene, the other a bit of scrolling text.</p>
 <ol type="1">
 <li>Redirect the output directly to vi, like this:</li>
 </ol>
-<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="ex">./schnitzi</span> <span class="op">&lt;</span> input.dat <span class="kw">|</span> <span class="fu">vi</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./schnitzi &lt; input.dat | vi</code></pre>
 <ol start="2" type="1">
 <li>Redirect the output to a file, like this:</li>
 </ol>
-<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">./schnitzi</span> <span class="op">&lt;</span> input.dat <span class="op">&gt;</span> output.dat</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./schnitzi &lt; input.dat &gt; output.dat</code></pre>
 <p>Then, open the output file, select the text, and copy it
 to your system pasteboard/cut/selection buffer and paste
 it into vi. The paste is NOT the vi paste command, but