[Groff] Proofed chapter 16

[Michael Hobgood]

I just sent Larry a proofed copy of chapter 16.

This completes the work on the chapters I've
worked on.  The proofreading was for content
only, and to get the example output as close
to the original as possible.  I made no attempts
to clean up widows/orphans etc.

It would be great if someone else would look
them over.  If you would like to and do find
an error, let me know.  I'll fix it.  

You will find my markup style barbaric.
I'll take comments on it; of course, I will
tend to agree more with you if you show me
a better way of doing it. And, especially
in chapter 15, you may find code that 
adeqately demonstrates that I don't know
what I'm doing most of the time.  Point
these out and my knowledge level will
improve.

It has been a pleasure to work on this project.

Cordially,
Michael Hobgood