Week-date time support
The Covid-19 pandemic of 2020/2021 generated increased interest in plotting
epidemiological data, which is often tabulated using a "week date" reporting
convention. Deficiencies with gnuplot support for this convention were
remedied and the support for week-date time was extended.
- Time specifier format %W has been brought into accord with the
ISO 8601 week date standard.
- Time specifier format %U has been brought into accord with the
CDC/MMWR week date standard.
- New function tm_week(time, std) returns ISO or CDC standard week of year.
- New function weekdate_iso(year, week, day) converts ISO standard week date
to calendar time.
- New function weekdate_cdc(year, week, day) converts CDC standard week date
to calendar time.
