Fix broken links
The w3 link validator says the following links are broken in index.html:
http://trac.common-lisp.net/cmucl/wiki/Release21adoc/index.html ahs these broken issues:
Line: 308 http://www.pmsf.de/resources/lisp/CMUCL.html
Status: 302 -> 404 Not Found
The link is broken. Double-check that you have not made any typo, or mistake in copy-pasting. If the link points to a resource that no longer exists, you may want to remove or fix the link.
 Line: 229 http://ww.telent.net/lisp/howto.html redirected to https://ww.telent.net/lisp/howto.html
Status: 301 -> 404 Not Found
The link is broken. Double-check that you have not made any typo, or mistake in copy-pasting. If the link points to a resource that no longer exists, you may want to remove or fix the link.
 Line: 213 https://www.common-lisp.net/project/cmucl/docs/internals/design/html/index.html
Status: 404 Not Found
The link is broken. Double-check that you have not made any typo, or mistake in copy-pasting. If the link points to a resource that no longer exists, you may want to remove or fix the link.
 Line: 364 http://psg.com/~dlamkins/sl/cover.html redirected to https://psg.com/~dlamkins/sl/cover.html
Status: 301 -> 404 Not Found
The link is broken. Double-check that you have not made any typo, or mistake in copy-pasting. If the link points to a resource that no longer exists, you may want to remove or fix the link.
 Line: 338 http://www.lisp.org/mop/ redirected to https://www.lisp.org/mop/
Status: 301 -> 404 Not Found
The link is broken. Double-check that you have not made any typo, or mistake in copy-pasting. If the link points to a resource that no longer exists, you may want to remove or fix the link.
 Line: 153 https://www.common-lisp.net/project/cmucl/downloads/doc/clx/
Status: 404 Not Found
The link is broken. Double-check that you have not made any typo, or mistake in copy-pasting. If the link points to a resource that no longer exists, you may want to remove or fix the link.
 Line: 342 http://www.dreamsongs.com/NewFiles/ECOOP.pdf
Status: 403 Forbidden
The link is forbidden! This needs fixing. Usual suspects: a missing index.html or Overview.html, or a missing ACL.
Line: 389 ftp://ftp.cs.cmu.edu/afs/cs/project/ai-repository/ai/lang/lisp/0.html
Status: 500 Name or service not known
This is a server side problem. Check the URI.
Line: 331 http://www.lispworks.com/reference/HyperSpec/Front/ redirected to http://www.lispworks.com/documentation/HyperSpec/Front/
Status: 301 -> 200 OK
This is a permanent redirect. The link should be updated.
 Line: 398 http://www.lisp.org/ redirected to https://www.lisp.org/
Status: 301 -> 200 OK
This is a permanent redirect. The link should be updated.
 Line: 380 http://cl-cookbook.sf.net/ redirected to http://cl-cookbook.sourceforge.net/
Status: 301 -> 200 OK
This is a permanent redirect. The link should be updated.
 Line: 352 http://www.naggum.no/worse-is-better.html redirected to http://naggum.no/worse-is-better.html
Status: 301 -> 200 OK
This is a permanent redirect. The link should be updated.