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/sds/README.md

@@ -1,6 +1,6 @@
 ## To build:
 
-```sh
+```<!---sh-->
     make
 ```
 
@@ -18,14 +18,14 @@ For more detailed information see [2004 sds bugs](../../bugs.html#2004_sds).
 
 ## To use:
 
-```sh
+```<!---sh-->
     ./sds
 ```
 
 
 ## Try:
 
-```sh
+```<!---sh-->
     ./try.sh
 ```
 
@@ -63,13 +63,13 @@ decoder.
 
 Try it out.  Compile the program, then type
 
-```sh
+```<!---sh-->
     ./sds < sds.c
 ```
 
 You should see the encoder program displayed.  Now save it, like:
 
-```sh
+```<!---sh-->
     ./sds < sds.c > encoder.c
 ```
 
@@ -82,14 +82,14 @@ standard input, and will output the results on the standard output.
 
 You can use it like this (assuming you have a file called remarks):
 
-```sh
+```<!---sh-->
     echo 'Hello, World!' > message
     ./encoder message < remarks > remarks_msg
 ```
 
 Then to decode:
 
-```sh
+```<!---sh-->
     ./sds < remarks_msg
     Hello, World!
 ```

2004/sds/index.html

@@ -141,15 +141,15 @@ Location: <a href="../../location.html#FI">FI</a> - <em>Republic of Finland </em
 <!-- 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>
 <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#2004_sds">2004 sds 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">./sds</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./sds</code></pre>
 <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">./try.sh</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./try.sh</code></pre>
 <h2 id="judges-remarks">Judges’ remarks:</h2>
 <p>Why not use the program to hide another program in the program? It
 must have seemed reasonable at the time.</p>
@@ -174,20 +174,20 @@ provide a separate encoding program, you should not be surprised to
 learn that I opted to steganographically hide the encoder inside the
 decoder.</p>
 <p>Try it out. Compile the program, then type</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">./sds</span> <span class="op">&lt;</span> sds.c</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./sds &lt; sds.c</code></pre>
 <p>You should see the encoder program displayed. Now save it, like:</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">./sds</span> <span class="op">&lt;</span> sds.c <span class="op">&gt;</span> encoder.c</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./sds &lt; sds.c &gt; encoder.c</code></pre>
 <p>Then compile <code>encoder.c</code>. You now have the complete system ready.</p>
 <p>The encoder expects to get a filename as an argument. This filename
 is the name of the file containing the information to be hidden. It
 expects the file in which to hide the information to be on the
 standard input, and will output the results on the standard output.</p>
 <p>You can use it like this (assuming you have a file called remarks):</p>
-<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="bu">echo</span> <span class="st">&#39;Hello, World!&#39;</span> <span class="op">&gt;</span> message</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./encoder</span> message <span class="op">&lt;</span> remarks <span class="op">&gt;</span> remarks_msg</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    echo &#39;Hello, World!&#39; &gt; message
+    ./encoder message &lt; remarks &gt; remarks_msg</code></pre>
 <p>Then to decode:</p>
-<div class="sourceCode" id="cb8"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./sds</span> <span class="op">&lt;</span> remarks_msg</span>
-<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a>    <span class="ex">Hello,</span> World!</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./sds &lt; remarks_msg
+    Hello, World!</code></pre>
 <p>C programs are mostly unaffected by adding steganographic content,
 but it is possible in certain circumstances for whitespace to be
 changed inside strings where it should be left alone. Plain text