pgsql: Add some additional casts and regression tests for the citext

Log Message:
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Add some additional casts and regression tests for the citext data type.
David Wheeler

Modified Files:
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    pgsql/contrib/citext:
        citext.sql.in (r1.2 -> r1.3)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/citext/citext.sql.in?r1=1.2&r2=1.3)
        uninstall_citext.sql (r1.2 -> r1.3)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/citext/uninstall_citext.sql?r1=1.2&r2=1.3)
    pgsql/contrib/citext/expected:
        citext.out (r1.2 -> r1.3)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/citext/expected/citext.out?r1=1.2&r2=1.3)
    pgsql/contrib/citext/sql:
        citext.sql (r1.2 -> r1.3)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/citext/sql/citext.sql?r1=1.2&r2=1.3)

Added Files:
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    pgsql/contrib/citext/expected:
        citext_1.out (r1.1)

(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/contrib/citext/expected/citext_1.out?rev=1.1&content-type=text/x-cvsweb-markup)