faceFan -- computes the fan generated by the cones over the faces

i1 : P = hypercube 2

o1 = {ambient dimension => 2           }
      dimension of lineality space => 0
      dimension of polyhedron => 2
      number of facets => 4
      number of rays => 0
      number of vertices => 4

o1 : Polyhedron

i2 : F = faceFan P

o2 = {ambient dimension => 2         }
      number of generating cones => 4
      number of rays => 4
      top dimension of the cones => 2

o2 : Fan

i3 : apply(maxCones F, rays)

o3 = {| -1 1 |, | -1 -1 |, | 1  1 |, | -1 1  |}
      | 1  1 |  | -1 1  |  | -1 1 |  | -1 -1 |

o3 : List