Angular separation to closest satellite

[bennahugo]

@rubyvanrooyen As mentioned it would be a very nice feature to implement zone of avoidances based on angular separation to satellite - or at least not count times when the target is within a few degrees from satellites towards observation time.

I've already implemented something along these lines in https://pypi.org/project/obzplan/
I've taken TLEs from https://www.space-track.org (at least all of them I could find) and added it to my database of objects to track. The result is a plot like the following for my submitted proposal:

[bennahugo]

(or at minimum print out nice fat warnings in the trial runs)