Vectorised version of `sp::spDistsN1()` over `pts` and `pt`?

[ramiromagno]

Hi,

Thanks for developing such a nice package.

I was wondering how to compute the Great Circle distance between points if my input are two sets of points, instead of a set of points and a point (as is expected by spDistsN1() and spDists()).

To be clear, if my two sets of points are saved in two matrices m1 and m2, I'd like to have an efficient solution, i.e., avoiding wrapping spDistsN1() in a loop and doing spDistsN1(m1[i, ], m2[i, ]) at each iteration. I'd rather have this iteration done internally at C code level. Is this available from {sp} anyhow?