[tz] USNO steps gingerly into the daylight saving mess

[Paul Eggert]

Last month the US Naval Observatory's Astronomical Applications Department 
published a web page that displays daylight saving starting and ending dates for 
US rules since 1967. A web page lets you enter a year like 1967 and the response 
will tell you start and end dates for that year. There is also an API that 
returns the data in a JSON format. Only US federal rules are supported, and only 
years from 1967 through 9999. See:

https://aa.usno.navy.mil/data/docs/daylight_time.php