Documentation updates (including log-view.8). No new functionality.
Add a flag to gdp-log-check to put an absolute limit on the record
number. This is to catch corrupt data files.
Add -t flag to gdp-log-check to act only on the timestamp index.
Add -s flag to gdp-log-check to show log status summaries only.
Distinguish between regular and severe errors when printing the summary
Add (minimal) documentation for gdp-log-check.