citext-to-and-from-xml tests, since those caused variation between
installations with or without libxml without really proving much. Instead
repurpose citext_1.out as the expected results in glibc en_US (and probably
other) locales.
of the STRING type category, thereby opening up the mechanism for user-defined
types. This is mainly for the benefit of citext, though; there aren't likely
to be a lot of types that are all general-purpose character strings.
Per discussion with David Wheeler.
