DoubleByteString is missing implementations of <= and >=. The
inherited implementation is case sensitive, unlike < and >.
< and > sort case-insensitive, with the exception of characters
that are equal ignoring case, in which the uppercase would be
before the lowercase.
As a result, <=, >=, and users of this such as the default sort of
SortedCollections, will not collate correctly with respect to case,
when DoubleByteStrings are the receiver in the comparison operation.
Copy the implementation of String >= and String <= to
DoubleByteString.
Last updated: 1/25/06