long edges?

[Fil]

Should the mesh contain the long edges? It would be more consistent to have that, and also include the large triangle, so that the union of all triangles would cover the whole globe. It's possible to do so now that the triangulation is clean, but it means we need to insert intermediate points when an edge is 180°.

Ref. daf7b88, reverted in daf7b88

(note: this would be a breaking change)