fix HTML problems related to pandoc and markdown image notation

Improve `make clobber` for `2004/anonymous`.

Instead of using this markdown element to embed an image:

```
![alt text](filename.png "Title")
```

Use a "img" HTML element with "alt", "alt", "width" and "length"
attributes:

```
<img src="filename.png"
 alt="describe the filename.png image for someone who cannot view it"
 width=PIXEL_WIDTH height=PIXEL_HEIGHT>
```

This was performed for:

```
2004/anonymous/index.html
2005/boutines/index.html
2011/goren/index.html
2012/vik/index.html
2013/birken/index.html
2013/cable1/index.html
2013/cable3/index.html
2013/hou/doc/example.html
2013/hou/index.html
2020/ferguson1/chocolate-cake.html
```

In the case of `2013/cable1/index.html` we reduce the displayed
image size by a factor for 2.  There is **NO** need to downsize the image
as this image size reduction produces a clean and sharp looking image.

In the case of `2013/hou/index.html` we reduce the displayed
image size by a factor for 2.  There is **NO** need to downsize the image
as this image size reduction produces a clean and sharp looking image.

In the case of `2020/ferguson1/chocolate-cake.html` we reduce the displayed
image size by a factor for 4.  There is **NO** need to downsize the image
as this image size reduction produces a clean and sharp looking image.

Run `make www` to perform the above.

2005/boutines/README.md

@@ -108,7 +108,9 @@ factors.
 
 Therefore this entry is limited to
 
-![floor\bigg(\frac{10^6}{4\times(sizeof(double)+1)}-1\bigg)](eqn.png)
+<img src="eqn.png"
+ alt="equation of the limit of the entry"
+ width=232 height=43>
 
 points and won't even be suitable for more than a few thousand; although
 generated files did pass the [W3C SVG
@@ -181,7 +183,9 @@ viewport and potentially every
 
 ### Example Output
 
-![Voronoi diagram of two regular pentagon vertices](Voronoi.png)
+<img src="Voronoi.png"
+ alt="image of example output: 5 regions of a 5-pointed star with 5 external regions beyond it"
+ width=542 height=542>
 
 
 <!--

2005/boutines/index.html

@@ -211,10 +211,9 @@ hard to qualify under the IOCCC size limit. So guess what I did? A compromise
 favoring innermost obfuscation, sacrificing sometimes speed and other tedious
 factors.</p>
 <p>Therefore this entry is limited to</p>
-<figure>
-<img src="eqn.png" alt="floor(-1)" />
-<figcaption aria-hidden="true">floor(-1)</figcaption>
-</figure>
+<p><img src="eqn.png"
+ alt="equation of the limit of the entry"
+ width=232 height=43></p>
 <p>points and won’t even be suitable for more than a few thousand; although
 generated files did pass the <a href="https://validator.w3.org/#validate_by_upload+with_options">W3C SVG
 Validator</a>, and are
@@ -266,10 +265,9 @@ viewport and potentially every
 <li><a href="http://www.snibbe.com/scott/bf">Voronoi and Art</a></li>
 </ul>
 <h3 id="example-output">Example Output</h3>
-<figure>
-<img src="Voronoi.png" alt="Voronoi diagram of two regular pentagon vertices" />
-<figcaption aria-hidden="true">Voronoi diagram of two regular pentagon vertices</figcaption>
-</figure>
+<p><img src="Voronoi.png"
+ alt="image of example output: 5 regions of a 5-pointed star with 5 external regions beyond it"
+ width=542 height=542></p>
 <!--
 
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