add archive tarballs

The archive/archive-YYYY.tar.bz2 compressed tarballs
came from the old IOCCC web site files of the form
YYYY/YYYY.tar.bz2.

The directories archive/YYYY/ are added to .gitignore
so that one may unpack all of the archives without
adding content to this repo.

TODO: Mention the archive/archive-YYYY.tar.bz2 compressed tarballs
      on the web site.  Perhaps a archive/README.md file would be best.

.gitignore

@@ -1,5 +1,32 @@
+.*.sw[a-z]
 .DS_Store
-prog
+/archive/1984/
+/archive/1985/
+/archive/1986/
+/archive/1987/
+/archive/1988/
+/archive/1989/
+/archive/1990/
+/archive/1991/
+/archive/1992/
+/archive/1993/
+/archive/1994/
+/archive/1995/
+/archive/1996/
+/archive/1998/
+/archive/2000/
+/archive/2001/
+/archive/2004/
+/archive/2005/
+/archive/2006/
+/archive/2011/
+/archive/2012/
+/archive/2013/
+/archive/2014/
+/archive/2015/
+/archive/2018/
+/archive/2019/
+/archive/2020/
 alt.prog
 mkentry
-.*.sw[a-z]
+prog