Polyhedra Package Changes Lineality Space of Fan

In some rare instances, the lineality space of a fan containing a single cone is different than the lineality space cone. This prevents adding cones to the fan that one should be able to add. Example:
```
i1 : loadPackage Polyhedra

o1 = Polyhedra

o1 : Package

i2 : v1 = matrix{{-2,-1, -1, 2, 0, 1, -1, 0, 0, 2}}
v2 = matrix {{-2,-1,0,0,1,0,0,1,0,1}}

o2 = | -2 -1 -1 2 0 1 -1 0 0 2 |

1 10
o2 : Matrix ZZ <-- ZZ

o3 = | -2 -1 0 0 1 0 0 1 0 1 |

1 10
o3 : Matrix ZZ <-- ZZ

i4 : image linealitySpace(fan coneFromHData(v1, v2)) == image linealitySpace(coneFromHData(v1, v2))

o4 = false
```
Perhaps this is intended behavior, apologies if so.

Reproduce the example using the Polyhedra package and compare linealitySpace(fan coneFromHData(...)) with linealitySpace(coneFromHData(...)). Start by locating the implementations of linealitySpace, fan, and coneFromHData; done means determining whether the differing spaces are a bug and, if so, adding a regression test for the example.

Written by the indexing model from the issue text.