I merged the refactor-mapped-buffer branch that we talked about to trunk.
Basically it straightens out the segment mapper hierarchy, implementing
some clean-ups Ted suggested. No functional changes, but ISTM much more
readable and maintainable.
Ted, I had to change some of your comments, basically those that referred
to problems that are now fixed, and in one case, changed to reflect my
understanding of InternalSegmentMapper naming. Please have a look and
tell me if you think there's a problem.
Tom Breton (Tehom)