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.

2012/hou/hint.md

@@ -2,13 +2,13 @@
 
 ### To build:
 
-```sh
+```<!---sh-->
     make hou
 ```
 
 ### To run:
 
-```sh
+```<!---sh-->
     ./hou syntax-file file-to-process
 ```
 
@@ -81,7 +81,7 @@ The following regular expression operators are supported:
 
 For example, one can use the following expression to match a certain declaration statement in hou.c:
 
-```c
+```<!---c-->
     "char"[ *]*[a-zA-Z_][0-9a-zA-Z_]*[ ]*((=[0-9a-zA-Z_ ]+)|(\[[0-9a-zA-Z_ ]*\]))?[ ]*(,[ *]*[a-zA-Z_][0-9a-zA-Z_]*[ ]*((=[0-9a-zA-Z_ ]+)|(\[[0-9a-zA-Z_ ]*\]))?[ ]*)*;
 ```
 
@@ -89,7 +89,7 @@ The regex engine is also algorithmically efficient. To illustrate the point,
 ansi.txt contains a pathological expression [2] that guarantees a hang for the
 competing Perl engine while matching itself. Try to compare these two engines:
 
-```sh
+```<!---sh-->
     ./hou ansi.txt ansi.txt
     perl patho.pl < ansi.txt
 ```