Update TODO list.

Index: TODO
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RCS file: /home/projects/pgsql/cvsroot/pgsql/doc/TODO,v
retrieving revision 1.306
diff -r1.306 TODO
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< Last updated:		Fri Dec 15 17:44:57 EST 2000
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> Last updated:		Thu Dec 21 14:12:04 EST 2000
31a32
> * Prevent BETWEEN from using duplicate nodes