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.

1998/banks/index.html

@@ -141,7 +141,7 @@ 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> all</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    make all</code></pre>
 <p>If you do not have a page up or page down key you might wish to see the
 <a href="#alternate-code">Alternate code</a> section below. You may redefine all the keys
 and the time step with predefined macros, however, so one lacking page up / page
@@ -164,11 +164,11 @@ Instructions</a> section.</p>
 to use. The name of the macro in the header file is what you need to set the
 macros to, depending on what controls you wish to redefine. For instance, to set
 the throttle up and down to <code>u</code> and <code>d</code>:</p>
-<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> clobber IT=XK_u DT=XK_d all</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    make clobber IT=XK_u DT=XK_d all</code></pre>
 <p>because in the header file you can see that <code>XK_u</code> corresponds to <code>u</code> and <code>XK_d</code>
 corresponds to <code>d</code>:</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 XK_d                             </span><span class="bn">0x0064</span><span class="pp">  </span><span class="co">/* U+0064 LATIN SMALL LETTER D */</span></span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a>    <span class="pp">#define XK_u                             </span><span class="bn">0x0075</span><span class="pp">  </span><span class="co">/* U+0075 LATIN SMALL LETTER U */</span></span></code></pre></div>
+<pre class="&lt;!---c--&gt;"><code>    #define XK_d                             0x0064  /* U+0064 LATIN SMALL LETTER D */
+    #define XK_u                             0x0075  /* U+0075 LATIN SMALL LETTER U */</code></pre>
 <p>Note that the <a href="keysym.h">keysym.h</a> file is not complete from X11; it’s just the
 more likely candidates (and some that are probably unlikely :-) ).</p>
 <p>The upper case letters would be <code>XK_U</code> and <code>XK_D</code> and you can search the header
@@ -181,7 +181,7 @@ instructions. Since you can use the original entry to redefine these this is not
 a problem and is purely a convenience .. if only for those who are okay with the
 preselected alternative keys.</p>
 <h2 id="to-use">To use:</h2>
-<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="fu">cat</span> horizon.sc pittsburgh.sc <span class="kw">|</span> <span class="ex">./banks</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    cat horizon.sc pittsburgh.sc | ./banks</code></pre>
 <p>See the author’s remarks in <a href="#scenery">scenery</a> for more details on the scenery
 files.</p>
 <h2 id="try">Try:</h2>
@@ -208,7 +208,7 @@ you should use the original entry as described in the to build section above.</p
 letters on the left side of the keyboard which is easier to use if one is using
 the right side for movement. These are hard coded, as noted.</p>
 <p>To use the default settings for the alternate build:</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="fu">make</span> alt</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    make alt</code></pre>
 <p>You may change the other keys as described in the build instructions, above, but
 this alt code can be seen as an alternative for those who don’t have or don’t
 want to use page up and page down.</p>
@@ -289,11 +289,11 @@ landscape.</p></li>
 <p>Follow a flowing river from the sky.</p></li>
 </ul>
 <p>A few examples of how to input scenery:</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="fu">cat</span> horizon.sc pittsburgh.sc <span class="kw">|</span> <span class="ex">./banks</span></span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a>    <span class="fu">cat</span> mountains.sc bb.sc <span class="kw">|</span> <span class="ex">./banks</span></span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a>    <span class="fu">cat</span> mountains.sc river.sc pyramids.sc <span class="kw">|</span> <span class="ex">./banks</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    cat horizon.sc pittsburgh.sc | ./banks
+    cat mountains.sc bb.sc | ./banks
+    cat mountains.sc river.sc pyramids.sc | ./banks</code></pre>
 <p>You can simulate flying through a cloud bank as well:</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">./banks</span> <span class="op">&lt;</span> /dev/null</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./banks &lt; /dev/null</code></pre>
 <p>You will usually want at least a horizon, though.</p>
 <p>The format of scenery files is simple, by the way. They’re just
 a list of 3D coordinates, and the simulator simply draws line