fix problematic HTML caused by certain trailing backslashes

In cases that are **outside of a markdown code block**,
a markdown line with ending in a tailing "\" can generate
problematic HTML.

We certain trailing backslashes outside of a markdown code block
with "<br>" HTML elements, or in some cases eliminated the
need for a trailing backslash.

In a few cases some unnecessary trailing backslashes inside
of a markdown code block were removed.

The following markdown files were changed in this commit:

```
1990/dds/README.md
1990/jaw/README.md
1991/ant/README.md
1991/rince/README.md
1991/westley/README.md
1992/vern/README.md
1992/westley/README.md
1998/schweikh1/README.md
2004/anonymous/README.md
2005/sykes/README.md
2006/toledo2/README.md
2011/toledo/README.md
2012/endoh2/README.md
2012/tromp/README.md
2013/robison/README.md
2015/hou/README.md
2015/howe/README.md
2015/schweikhardt/README.md
2018/burton1/README.md
2018/burton2/README.md
2018/ferguson/README.md
2018/vokes/README.md
2020/ferguson1/README.md
```

Performed `make www` to test these changes.

1992/vern/README.md

@@ -125,7 +125,7 @@ initial source is gloriously difficult to peruse. In particular, the Makefile
 does:
 
 ``` <!---sh-->
-    sed <vern.c 's/{ /(/g;s/} /)/g;s/;       /#define /' | \
+    sed <vern.c 's/{ /(/g;s/} /)/g;s/;       /#define /' |
 	sed 's/}      /=/g;s/{        /i/g' >vern.tmp.c
 ```
 

1992/vern/index.html

@@ -235,7 +235,7 @@ at build time into much-needed text. Without this hack the program
 wouldn’t pass the character limit. A nice side effect is that the
 initial source is gloriously difficult to peruse. In particular, the Makefile
 does:</p>
-<pre><code>    sed &lt;vern.c &#39;s/{ /(/g;s/} /)/g;s/;       /#define /&#39; | \
+<pre><code>    sed &lt;vern.c &#39;s/{ /(/g;s/} /)/g;s/;       /#define /&#39; |
         sed &#39;s/}      /=/g;s/{        /i/g&#39; &gt;vern.tmp.c</code></pre>
 <p>and compiles <code>vern.tmp.c</code>.</p>
 <p>Second, the rather ho-hum step has been taking of naming each variable

1992/westley/README.md

@@ -150,16 +150,18 @@ is reasonably accurate.
 
 ### Here are some cities you might like to try:
 
-- New York	    41   -74\
-- London	    52   0\
-- Moscow	    56   38\
-- New Delhi	    29   77\
-- Sydney	    -34  151
-- Los Angeles	    34   -118
-- Paris		    45   2
-- Rio de Janeiro    -23  -43
-- Beijing	    40   116
-- Tokyo		    36   140
+```
+    New York	     41  -74
+    London	     52   0
+    Moscow	     56   38
+    New Delhi	     29   77
+    Sydney	    -34   151
+    Los Angeles	     34  -118
+    Paris	     45   2
+    Rio de Janeiro  -23  -43
+    Beijing	     40   116
+    Tokyo	     36   140
+```
 
 
 For a domestic (US) version with higher resolution, try:

1992/westley/index.html

@@ -236,22 +236,16 @@ blank line. It’s just for show, really.</p>
 be just off the map; this is an unavoidable artifact. The map
 is reasonably accurate.</p>
 <h3 id="here-are-some-cities-you-might-like-to-try">Here are some cities you might like to try:</h3>
-<ul>
-<li>New York 41 -74<br />
-</li>
-<li>London 52 0<br />
-</li>
-<li>Moscow 56 38<br />
-</li>
-<li>New Delhi 29 77<br />
-</li>
-<li>Sydney -34 151</li>
-<li>Los Angeles 34 -118</li>
-<li>Paris 45 2</li>
-<li>Rio de Janeiro -23 -43</li>
-<li>Beijing 40 116</li>
-<li>Tokyo 36 140</li>
-</ul>
+<pre><code>    New York         41  -74
+    London           52   0
+    Moscow           56   38
+    New Delhi        29   77
+    Sydney          -34   151
+    Los Angeles      34  -118
+    Paris            45   2
+    Rio de Janeiro  -23  -43
+    Beijing          40   116
+    Tokyo            36   140</code></pre>
 <p>For a domestic (US) version with higher resolution, try:</p>
 <pre><code>    main(l,a,n,d)char**a;{for(d=atoi(a[1])/2*80-atoi(a[2])-2043;
     n=&quot;bnaBCOCXdBBHGYdAP[A M E R I C A].AqandkmavX|ELC}BOCd&quot;