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.

1993/schnitzi/README.md

@@ -1,6 +1,6 @@
 ## To build:
 
-```sh
+```<!---sh-->
     make all
 ```
 
@@ -18,7 +18,7 @@ For more detailed information see [1993 schnitzi bugs](../../bugs.html#1993_schn
 
 ## To use:
 
-```sh
+```<!---sh-->
     ./schnitzi file
 ```
 
@@ -33,14 +33,14 @@ in [1993 schnitzi bugs](../../bugs.html#1993_schnitzi).
 
 ## Try:
 
-```sh
+```<!---sh-->
     ./schnitzi schnitzi.info
     # ask some questions suggested by the author, noted below
 ```
 
 We also suggest you ask the program the following questions:
 
-```sh
+```<!---sh-->
     Who is Mark Schnitzus?
 
     Who was Jack the Ripper ?
@@ -51,7 +51,7 @@ intentional spelling error there.
 
 Try feeding the program source to the program and ask both:
 
-```sh
+```<!---sh-->
     What is cat ?
     What is cat?
 ```

1993/schnitzi/index.html

@@ -141,29 +141,29 @@ 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>
 <h3 id="bugs-and-misfeatures">Bugs and (Mis)features:</h3>
 <p>The current status of this entry is:</p>
 <pre><code>    STATUS: INABIAF - please **DO NOT** fix</code></pre>
 <p>For more detailed information see <a href="../../bugs.html#1993_schnitzi">1993 schnitzi 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">./schnitzi</span> file</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./schnitzi file</code></pre>
 <p>where</p>
 <p><code>file</code> is a file containing some text.</p>
 <p>Certain input will cause the program to fail as described
 in <a href="../../bugs.html#1993_schnitzi">1993 schnitzi bugs</a>.</p>
 <h2 id="try">Try:</h2>
-<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="ex">./schnitzi</span> schnitzi.info</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a>    <span class="co"># ask some questions suggested by the author, noted below</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./schnitzi schnitzi.info
+    # ask some questions suggested by the author, noted below</code></pre>
 <p>We also suggest you ask the program the following questions:</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="ex">Who</span> is Mark Schnitzus<span class="pp">?</span></span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a>    <span class="ex">Who</span> was Jack the Ripper <span class="pp">?</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    Who is Mark Schnitzus?
+
+    Who was Jack the Ripper ?</code></pre>
 <p>Notice how it still manages to answer the first question despite there being an
 intentional spelling error there.</p>
 <p>Try feeding the program source to the program and ask both:</p>
-<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">What</span> is cat <span class="pp">?</span></span>
-<span id="cb6-2"><a href="#cb6-2" aria-hidden="true" tabindex="-1"></a>    <span class="ex">What</span> is cat<span class="pp">?</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    What is cat ?
+    What is cat?</code></pre>
 <p>What happens if you ask it other questions with and without a space before the
 <code>?</code>?</p>
 <h2 id="judges-remarks">Judges’ remarks:</h2>