Further review of range-types patch.

doc/src/sgml/catalogs.sgml

doc/src/sgml/extend.sgml

doc/src/sgml/func.sgml

doc/src/sgml/rangetypes.sgml

doc/src/sgml/ref/create_type.sgml

doc/src/sgml/rowtypes.sgml

src/bin/pg_dump/pg_dump.c

src/bin/pg_dump/pg_dump_sort.c

src/include/catalog/pg_range.h

src/include/catalog/pg_type.h

src/test/regress/expected/type_sanity.out

src/test/regress/sql/type_sanity.sql