geodesic code

[visr]

When this package was still called Proj4.jl the geodesic functions were offered in a higher level interface: proj_geodesic.jl. It might be nice to restore such an interface.

The geodesic ccall functions are still in libproj.jl, they start with geod_. So anyone familiar with the API should be able to use it.

https://proj.org/geodesic.html
https://geographiclib.sourceforge.io/1.52/C/
https://geographiclib.sourceforge.io/1.52/C/geodesic_8h.html