BUG: fixed a bug in IntersectWithLine method, which doesn't use a vtkPolygon anymore to compute prism ends intersection.
BUG: the reason for that is vtkPolygon does not correctly detect intersections with line unless it's perfectly plannar,
BUG: which is almost never the case in the real world.
BUG: additionally, fixed a potential segfault in pentagonalPrism that has only 5 quad faces but used to iterate over 7 (probably a bad copy/paste from hexagonalPrism)