Add horizontalToEquatorial method to astropysics.obstools.Site class

[peterjc]

The equatorialToHorizontal method looks great, but I want the inverse as well - given local horizontal coordinates (e.g. Altitude/Azimuth from an instrumented telescope), calculate the equatorial coordinates (RA/Dec), based on the site's location and time.

(I saw on @eteq mention on another issue possibly redirecting efforts to astropy, see also astropy/astropy-api#6 about adding similar functionality to astropy)

[eteq]

@peterjc - Thanks, yeah, this is definitely a useful thing to have, but it would take a fair amount of work to do it right in astropysics, and I'd rather do it in astropy. I'll leave this open at least until it's in astropy, though.

[eteq]

@peterjc - Note that this functionality is now present in astropy as of v1.0 - see this example for how it can be used. Hence, I'm closing this in astropysics as "will not fix" so as to reduce duplication of effort.

[peterjc]

Thank you