Porter's Handbook PRs (FYI for those who don't read -doc)

[Mark Linimon]

I have submitted a set of 5 PRs against the Porter's Handbook
to -doc.  They are based on some work that I did several weeks
ago that was reviewed by Tilman and Giorgios.  In fact, Giorgios
was interested in committing it but ran out of time before he had to
go off for a year.

Further comments are welcome.

mcl