Various fixes and updates

Make lines beginning (in markdown files) 'BTW' bold. Rebuilt the
respective html pages.

Slight update to abstract in two entries (1985/shapiro and
1994/shapiro). One is changing 'defines' to '#defines' and the other was
a typo fix.

Fixed make gen_next: added missing new files.

Various fixes in next/register.html (typos and other things).

1998/schnitzi/README.md

@@ -60,7 +60,7 @@ have output which depends on anything?
 For hints on deciphering this, see below past the Author's remarks;
 they're a nice summary, but they leave the mystery intact.
 
-BTW: the author notes an incredible
+**BTW**: the author notes an incredible
 [lipogram](https://en.wikipedia.org/wiki/Lipogram) story called
 [Gadsby](https://www.gutenberg.org/cache/epub/47342/pg47342.txt) which has no
 letter `E` in the story. He did not note this but it has over `50000` (50

1998/schnitzi/index.html

@@ -479,7 +479,7 @@ the fixes for modern systems although there are still no <code>if</code>s) behav
 have output which depends on anything?</p>
 <p>For hints on deciphering this, see below past the Author’s remarks;
 they’re a nice summary, but they leave the mystery intact.</p>
-<p>BTW: the author notes an incredible
+<p><strong>BTW</strong>: the author notes an incredible
 <a href="https://en.wikipedia.org/wiki/Lipogram">lipogram</a> story called
 <a href="https://www.gutenberg.org/cache/epub/47342/pg47342.txt">Gadsby</a> which has no
 letter <code>E</code> in the story. He did not note this but it has over <code>50000</code> (50