Fix author URLs

All the authors now have either a null URL, a valid URL or one on the
Internet Wayback Machine.

Where it seemed likely (say because the domain no longer exists) emails
were set to null also.

Now unless a bug is found in the script this really should finish the
checks of authors.html.

author/Jim_Hague.json

@@ -5,8 +5,8 @@
     "full_name" : "Jim Hague",
     "sort_word" : "hague",
     "location_code" : "GB",
-    "email" : "jim.hague@acm.org",
-    "url" : "http://www.oxinet.co.uk/jim",
+    "email" : null,
+    "url" : "https://web.archive.org/web/19991003012715/http://www.oxinet.co.uk/jim/",
     "alt_url" : null,
     "deprecated_twitter_handle" : null,
     "mastodon" : null,