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.

2015/hou/README.md

@@ -1,6 +1,6 @@
 ## To build:
 
-```sh
+```<!---sh-->
     make
 ```
 
@@ -18,7 +18,7 @@ For more detailed information see [2015 hou bugs](../../bugs.html#2015_hou).
 
 ## To use:
 
-```sh
+```<!---sh-->
     echo something | ./prog
     ./prog < file
 ```
@@ -26,7 +26,7 @@ For more detailed information see [2015 hou bugs](../../bugs.html#2015_hou).
 
 ## Try:
 
-```sh
+```<!---sh-->
     ./try.sh
 ```
 
@@ -42,7 +42,7 @@ the reference code!
 
 Some things that make you go, "huh?"
 
-```sh
+```<!---sh-->
     ./prog < prog.c | cut -c-5
     ./prog < Makefile | cut -c-4
 ```
@@ -51,7 +51,7 @@ How are those values magically returned?
 
 What happens with a large file? Something over 256K.
 
-```sh
+```<!---sh-->
     ./prog < large_file
 ```
 

2015/hou/index.html

@@ -141,16 +141,16 @@ Location: <a href="../../location.html#CN">CN</a> - <em>People’s Republic of C
 <!-- 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#2015_hou">2015 hou 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="bu">echo</span> something <span class="kw">|</span> <span class="ex">./prog</span></span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./prog</span> <span class="op">&lt;</span> file</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    echo something | ./prog
+    ./prog &lt; file</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>A good start for understanding this entry might be
 <a href="rfc1321.txt">rfc1321.txt</a>. How does it compute this using only a
@@ -159,11 +159,11 @@ algorithm is about 355 lines of code, yet this entry is only 199 lines with
 one statement per line and it isn’t using lots of macro expansion tricks like
 the reference code!</p>
 <p>Some things that make you go, “huh?”</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">./prog</span> <span class="op">&lt;</span> prog.c <span class="kw">|</span> <span class="fu">cut</span> <span class="at">-c-5</span></span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./prog</span> <span class="op">&lt;</span> Makefile <span class="kw">|</span> <span class="fu">cut</span> <span class="at">-c-4</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./prog &lt; prog.c | cut -c-5
+    ./prog &lt; Makefile | cut -c-4</code></pre>
 <p>How are those values magically returned?</p>
 <p>What happens with a large file? Something over 256K.</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">./prog</span> <span class="op">&lt;</span> large_file</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./prog &lt; large_file</code></pre>
 <p>Where does that message come from?</p>
 <h2 id="authors-remarks">Author’s remarks:</h2>
 <p>This looks like a normal C program.</p>