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don't crash if meshMaster is not available (can happen e.g. if tag has been changed after face creation)

(this way we can use it with a geo obtained from createTopologyFromMesh, which does
not currently reorder line loops)

Added option for levelset cutting ""CutMeshTri(tag)", that saves only triangles and tets (no polygons or polyhedra)
Added new level set definition "Levelset Points(tag)={{x1,y1,z1},{x2,y2,z2}};", builds a level set from a set of data points using RBF interpolation

with tet meshes using pyramids.

It's not perfect (it introduces the pyramids in the extruded/transfinite mesh) but it's useful
nonetheless.