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.

2006/night/README.md

@@ -1,6 +1,6 @@
 ## To build:
 
-```sh
+```<!---sh-->
     make
 ```
 
@@ -10,7 +10,7 @@ code](#alternate-code) section below.
 
 ## To use:
 
-```sh
+```<!---sh-->
     ./night
 ```
 
@@ -23,7 +23,7 @@ keys.
 
 ### Alternate build:
 
-```sh
+```<!---sh-->
     make alt
 ```
 
@@ -129,7 +129,7 @@ to deobfuscate.
 Keypad support was removed to save space. To restore, modify the
 following two macros to:
 
-```c
+```<!---c-->
     #define ATG srand(time(0)); initscr(); cbreak(); noecho(); start_color(); keypad(stdscr,1);
     #define AGG A&2?KEY_UP:KEY_DOWN:A&1?KEY_RIGHT:KEY_LEFT
 ```

2006/night/index.html

@@ -141,16 +141,16 @@ 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 that supports arrow keys. See the <a href="#alternate-code">alternate
 code</a> section below.</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">./night</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./night</code></pre>
 <h2 id="alternate-code">Alternate code:</h2>
 <p>This version allows you to use arrow keys instead of the more awkward <code>wasd</code>
 keys.</p>
 <h3 id="alternate-build">Alternate build:</h3>
-<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="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>night.alt</code> as you would <code>night</code> above.</p>
 <h2 id="judges-remarks">Judges’ remarks:</h2>
@@ -217,8 +217,8 @@ preprocessed code is over 80KB in length, hindering the preprocessor’s ability
 to deobfuscate.</p>
 <p>Keypad support was removed to save space. To restore, modify the
 following two macros to:</p>
-<div class="sourceCode" id="cb4"><pre class="sourceCode c"><code class="sourceCode c"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a>    <span class="pp">#define ATG srand</span><span class="op">(</span><span class="pp">time</span><span class="op">(</span><span class="dv">0</span><span class="op">));</span><span class="pp"> initscr</span><span class="op">();</span><span class="pp"> cbreak</span><span class="op">();</span><span class="pp"> noecho</span><span class="op">();</span><span class="pp"> start_color</span><span class="op">();</span><span class="pp"> keypad</span><span class="op">(</span><span class="pp">stdscr</span><span class="op">,</span><span class="dv">1</span><span class="op">);</span></span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a>    <span class="pp">#define AGG A</span><span class="op">&amp;</span><span class="dv">2</span><span class="op">?</span><span class="pp">KEY_UP</span><span class="op">:</span><span class="pp">KEY_DOWN</span><span class="op">:</span><span class="pp">A</span><span class="op">&amp;</span><span class="dv">1</span><span class="op">?</span><span class="pp">KEY_RIGHT</span><span class="op">:</span><span class="pp">KEY_LEFT</span></span></code></pre></div>
+<pre class="&lt;!---c--&gt;"><code>    #define ATG srand(time(0)); initscr(); cbreak(); noecho(); start_color(); keypad(stdscr,1);
+    #define AGG A&amp;2?KEY_UP:KEY_DOWN:A&amp;1?KEY_RIGHT:KEY_LEFT</code></pre>
 <p>Code on!</p>
 <!--