Function circadia::time_of_event

pub fn time_of_event(
    date: Date<Utc>, 
    pos: &GlobalPosition, 
    event: SunEvent
) -> Option<DateTime<Utc>>

Calculates the time of the sunrise/sunset on the given date at the given position on the globe.

This is an implementation of the algorithm described by the United states Naval Observatory found here: http://edwilliams.org/sunrise_sunset_algorithm.htm

Returns None if the sun never sets/rises on that day (ie if you're in the arctic).