add rules, guidelines, fix HTML code, move compressed tarball in inventory

By changing the _inventory_order_ of the compressed tarball from
**100000** to **1415926535**, the compressed tarball will land at
the top of the secondary file list and remain still easy to find.

Updated the `manifest.numbers` spreadsheet and rebuilt
the `.entry.json` files.

Added `next/` directory to hold the next IOCCC rules and guidelines.
Added `next/README.md` that `bin/gen-top-html.sh` uses to form
the `next/index.html` file.

Added _Rules and Guidelines_ link to the sidenav bar to link to the
`next/index.html` file.

Added _IOCCC Rules_ as `next/rules.md` that `bin/gen-top-html.sh`
uses to form the `next/rules.html` file.

Added _IOCCC Guidelines_ as `next/guidelines.md` that `bin/gen-top-html.sh`
uses to form the `next/guidelines.html` file.

Changed `bin/gen-top-html.sh` VERSION from "1.2.4 2024-04-13"
to "1.3 2024-04-14".

Prevent `pandoc(1)` from interpreting the commented out language
of a markdown code block as a code class.  So a markdown such as:

````
``` <!---sh-->
...
```
````

that produced HTML of the form:

```html
<pre class="&lt;!---sh--&gt;"><code>...</code></pre>
```

will now produce HTML of the form:

```html
<pre><code>...</code></pre>
```

NOTE: Before when the language of a markdown code block
was not commented, the HTML produced by `pandoc(1)` was
oddly indented with extra whitespace on the first line
of the code block.  While commenting out the language
of the code block removed some of the odd intending,
it left a weird class in the HTML pre block that
surrounded the HTML code block.  This hack prevents
`pandoc(1)` from assigning a class to the HTML pre block.

Changed `in/md2html.sh` VERSION from "1.2.1 2024-04-13"
to "1.3 2024-04-14".

Added `make gen_sitemap` to end of both `make www` and `make
quick_www` in top level Makefile.

Ram `make www` to test under macOS and to perform the above.

**IMPORTANT NOTE**: The current `next/rules.md` and `next/guidelines.md`
are simply the 2020 IOCCC Rules and Guidelines converted into
markdown form.  There are **NOT** the Rules and Guidelines that
will be used the IOCCC MOCK, nor the next IOCCC.

TODO: Improve the `bin/gen-status.sh` tool to modify the top of the
      `next/rules.md` and `next/guidelines.md` files to keep them
      in sync with the _contest_status_ as found in `status.json`.

TODO: Improve the look and feel of the `next/rules.md` and
      `next/guidelines.md` markdown files.

1996/eldby/index.html

@@ -88,6 +88,7 @@
     <div class="sidenav">
       <a href="../../news.html">IOCCC News</a>
       <a href="../../status.html">Contest status</a>
+      <a href="../../next/index.html">Rules and Guidelines</a>
       <a href="../../faq.html#submit">How to enter the IOCCC</a>
       <a href="../../faq.html">FAQ</a>
     </div>
@@ -141,12 +142,12 @@ Location: <a href="../../location.html#ZZ">ZZ</a> - <em>Unknown location</em></l
 <!-- 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>
-<pre class="&lt;!---sh--&gt;"><code>    make alt</code></pre>
+<pre><code>    make alt</code></pre>
 <p>We recommend that you use the alt version to see what the entry looked like back
 in 1996. For the original version see the <a href="#original-code">original code</a>
 section.</p>
 <h2 id="to-use">To use:</h2>
-<pre class="&lt;!---sh--&gt;"><code>    ./eldby.alt</code></pre>
+<pre><code>    ./eldby.alt</code></pre>
 <p>To quit send intr (typically ctrl-c).</p>
 <p>NOTE: to reset the sanity of your terminal after this program ends try <code>reset</code>.</p>
 <h2 id="try">Try:</h2>
@@ -155,12 +156,12 @@ happening with modern systems, and to not flash too quickly, which can be
 problematic for some people, can be configured to different speeds by way of the
 value used in <code>usleep()</code>. The default is <code>35000</code> but you can easily change
 it. To do so try:</p>
-<pre class="&lt;!---sh--&gt;"><code>    make SLEEP=20000 clobber alt
+<pre><code>    make SLEEP=20000 clobber alt
     ./eldby.alt</code></pre>
 <h2 id="original-code">Original code:</h2>
 <p>This version is the original which has no sleep time in between updates.</p>
 <h3 id="original-build">Original build:</h3>
-<pre class="&lt;!---sh--&gt;"><code>    make all</code></pre>
+<pre><code>    make all</code></pre>
 <h3 id="original-use">Original use:</h3>
 <p>Use <code>./eldby</code> as you would <code>./eldby.alt</code> above.</p>
 <h2 id="judges-remarks">Judges’ remarks:</h2>
@@ -197,10 +198,10 @@ must be VT100 or better with 80 columns and 24 rows or more.</p>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1996/eldby/Makefile">Makefile</a> - entry Makefile</li>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1996/eldby/eldby.alt.c">eldby.alt.c</a> - alternative source</li>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1996/eldby/eldby.orig.c">eldby.orig.c</a> - original source</li>
-<li><a href="1996_eldby.tar.bz2">1996_eldby.tar.bz2</a> - download entry tarball</li>
 </ul>
 <h2 id="secondary-files">Secondary files</h2>
 <ul>
+<li><a href="1996_eldby.tar.bz2">1996_eldby.tar.bz2</a> - download entry tarball</li>
 <li><a href="index.html">index.html</a> - this web page</li>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1996/eldby/README.md">README.md</a> - markdown source for this web page</li>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1996/eldby/.entry.json">.entry.json</a> - description of entry in JSON</li>