igl::ismember_rows

[alecjacobson]

AFAICT numpy doesn't have a good solution for this. Here's a literal python port but python's for loops are dreadfully slow. Would be nice to just wrap the fast libigl one:

[alecjacobson]

The array_correspondence in gpytoolbox https://gpytoolbox.org/0.0.3/array_correspondence/ also works in the meantime.