Massive fiddling to reflect that datetimetz and timetz no longer exist.

Massive fiddling to reflect that datetimetz and timetz no longer exist.
WARNING:  It would be a minor miracle if the LaTeX stuff still worked.

s/field/member/ generally everywhere, to conform with most other usage in
the docs.

s/daylight savings time/daylight saving time/ generally everywhere,
because the latter spelling is anally correct.