Make SQL arrays support null elements. This commit fixes the core array

functionality, but I still need to make another pass looking at places
that incidentally use arrays (such as ACL manipulation) to make sure they
are null-safe.  Contrib needs work too.
I have not changed the behaviors that are still under discussion about
array comparison and what to do with lower bounds.

doc/src/sgml/ref/insert.sgml

@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/insert.sgml,v 1.29 2005/01/09 05:57:45 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/insert.sgml,v 1.30 2005/11/17 22:14:51 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -206,11 +206,11 @@ INSERT INTO films SELECT * FROM tmp_films WHERE date_prod &lt; '2004-05-07';
 
 <programlisting>
 -- Create an empty 3x3 gameboard for noughts-and-crosses
--- (these commands create the same board)
 INSERT INTO tictactoe (game, board[1:3][1:3])
-    VALUES (1,'{{"","",""},{"","",""},{"","",""}}');
+    VALUES (1, '{{" "," "," "},{" "," "," "},{" "," "," "}}');
+-- The subscripts in the above example aren't really needed
 INSERT INTO tictactoe (game, board)
-    VALUES (2,'{{,,},{,,},{,,}}');
+    VALUES (2, '{{X," "," "},{" ",O," "},{" ",X," "}}');
 </programlisting>
   </para>
  </refsect1>