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).

2020/ferguson2/recode.md

@@ -637,7 +637,7 @@ think that I would give too much away? :)
     0MC4OH2CO1LATEUMBJCDFGHINOPRQS
 ```
 
-BTW: what's the middle of a list with even numbered items anyway?
+**BTW**: what's the middle of a list with even numbered items anyway?
 
 To help you out, though, this is how you might do the decrypting. Assuming that
 the key you wish to select is