Helper functions for working with elm/time
toDateString : Time.Posix -> String
Uses Iso8601.fromTime produces a date with timestamp and takes first 10 characters to return "YYYY-MM-DD"
offsetYear : Basics.Int -> Time.Posix -> Time.Posix
Offsets a time by the given number of years and returns a new time, floored to the start of the year.
offsetDay : Basics.Int -> Time.Posix -> Time.Posix
Offsets a time by the given number of days and returns a new time, floored to the start of the day.