[RndTbl] Cron entries for sunrise and sunset

[Trevor Cordes]

On 2020-07-04 Troy Denton wrote:
> A fun side project of mine - I've patched the Debian 'cron' source to
> provide @sunrise and @sunset, similar to @reboot

That's a really cool idea.  Looks like you're doing it all with math
and no external (web) lookups?  How long does just the math way stay
accurate?  Don't you need to account for wobble and things that may
subtly change over time (assuming they do, I thought something did)?

You should crisp it up as much as possible and submit it to the cron
upstream!  Has to be self-contained, clean and accurate though
(probably).

Good clean code layout.  Nice.  Extra hero cookie for C.