astrog improvements

[veenstrajelmer]

Todo:

• [x] https://github.com/Deltares/hatyan/issues/332
• [x] https://github.com/Deltares/hatyan/issues/338
• [x] https://github.com/Deltares/hatyan/issues/346
• [ ] when calling hatyan.astrog.astrog_culminations(tFirst="18870101",tLast="20221231") it raises "Exception: Requested time out of range (1900-2091)". This is not necessary to change, but would be convenient anyway
• [ ] https://github.com/Deltares/hatyan/issues/323
• [ ] astrog reproduction works, but not everything works for all coordinates
• [ ] consider moving to pyephem or other python astro package (of astropy of pint voor units)
• [ ] consider moving astrog to separate package