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.

2020/ferguson1/troubleshooting.html

@@ -372,7 +372,7 @@ hit a key every time to move because it is blocking.</p></li>
 </ul>
 <h2 id="on-environmental-variables-more-generally-and-string-to-int-conversions"><a name="envvars" href="#toc">On environmental variables more generally and string to int conversions</a></h2>
 <p>What happens if you do:</p>
-<div class="sourceCode" id="cb12"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a>    <span class="va">WALLS</span><span class="op">=</span> <span class="ex">./prog</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    WALLS= ./prog</code></pre>
 <p>Can you run into the wall since you didn’t specify a value and the default is 1?
 No. That’s not the way it works. By saying WALLS= you have told the system that
 there is that environmental variable. However the way the <code>strtoul()</code> functions
@@ -381,12 +381,12 @@ it’s wasteful (iocccsize wise) and I have never felt that having invalid input
 for a number could have a better value than 0.</p>
 <p>If however you were to give valid input followed by invalid input the valid
 input would be parsed. For example:</p>
-<div class="sourceCode" id="cb13"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>    <span class="va">WALLS</span><span class="op">=</span>1test <span class="ex">./prog</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    WALLS=1test ./prog</code></pre>
 <p>would let you go through the walls. On the other hand</p>
-<div class="sourceCode" id="cb14"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>    <span class="va">WALLS</span><span class="op">=</span>test1 <span class="ex">./prog</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    WALLS=test1 ./prog</code></pre>
 <p>would not. Furthermore if you specify the same variable more than once it’s the
 last one that counts. For example:</p>
-<div class="sourceCode" id="cb15"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a>    <span class="va">WALLS</span><span class="op">=</span>0 <span class="va">WALLS</span><span class="op">=</span>1 <span class="va">CANNIBAL</span><span class="op">=</span>1 <span class="va">CANNIBAL</span><span class="op">=</span>0 <span class="ex">./prog</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    WALLS=0 WALLS=1 CANNIBAL=1 CANNIBAL=0 ./prog</code></pre>
 <p>would allow you to go through walls but you could not cannibalise.</p>
 <p>Also note that I specify base 0 which means that you can also have it in hex and
 octal. These are all the same:</p>
@@ -421,17 +421,17 @@ will end (yes things that haven’t begun can be ended).</p>
 <p>If <code>calloc()</code> fails to obtain the needed memory you’ll see something like (here it
 was before I added proper - to make the perfect and obvious pun - capsizing
 so that by setting the size to -1 it went to the max unsigned value):</p>
-<div class="sourceCode" id="cb19"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a>    <span class="ex">$</span> MAXSIZE=-1 ./prog</span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>    <span class="ex">memory</span> error</span>
-<span id="cb19-3"><a href="#cb19-3" aria-hidden="true" tabindex="-1"></a>    <span class="ex">X:0/157</span> Y:0/42 S:3/18446744073709551614 B:0</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    $ MAXSIZE=-1 ./prog
+    memory error
+    X:0/157 Y:0/42 S:3/18446744073709551614 B:0</code></pre>
 <p>BTW: There are two arrays that have to be <strong>MAXSIZE</strong> (technically + 1).</p>
 <p>Is it possible that some value specified by the user could mess this up? I do
 not know but what I do know is that because it’s unsigned it can’t be negative;
 if the max size is 0 then the array size will be 1 but it won’t matter because
 the snake size will be &gt;= that max anyway. But here’s a curious output:</p>
-<div class="sourceCode" id="cb20"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>    <span class="va">SIZE</span><span class="op">=</span>1 <span class="va">MAXSIZE</span><span class="op">=</span>0 <span class="ex">./prog</span></span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a>    <span class="ex">YOU</span> WIN!</span>
-<span id="cb20-3"><a href="#cb20-3" aria-hidden="true" tabindex="-1"></a>    <span class="ex">X:78/156</span> Y:20/41 S:0/0 B:0</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    SIZE=1 MAXSIZE=0 ./prog
+    YOU WIN!
+    X:78/156 Y:20/41 S:0/0 B:0</code></pre>
 <p>Why does it show snake size as 0 when I specified 1? It’s because the max size
 is 0 and I limit the size to be no bigger than the max size.</p>
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