Update meshRefine.cpp

Changing the Subdivision scheme of 2nd order triangle. The previous one was computing parametric coordinates from all the 6-nodes, internally making 6-nonlinear calculations, instead we get the closestPoint() of the barycenter allow to do the same calculation once and obtain the parametric coordinates, besides, with a test on spherical surface, a primary node (1-3) may lie upon the end-point, which happen to be the start and the end as well having 2 valid values, as (2PI and 0). The previous approach cannot distinguish the two. Hence, obtaining the parametric value from the projection of the cartesian barycenter, is less expensive and more reliable for periodic surfaces.