describe the change to hashcodes of matrices

... in the documentation node "changes, 1.7"
fix an ordering of rays of a fan

In the packages Polyhedra and ToricVectorBundles, the rays of a fan are
stored in a hash table, and the sequence they are displayed in is
determined by the algorithms for normalFan and convexHull, as well as by
the way hash codes of matrices of integers are computed.  We have
recently improved, with commit 78c525c9d36c9d26c38c7cb124681a7851a4aa63,
the hash codes of matrices.  As a result, the displayed ordering of the
rays of a fan changed, and 9 tests in the package ToricVectorBundles
started failing.

In this commit we fix an ordering of the rays of a fan (see the new
private function raySort in the package Polyhedra), and we alter the
tests so they succeeed.  The ordering we choose is close to the
former (accidental) ordering.

Here is a comparison of the ray ordering for projective space.

Before:

    i3 : netList for i from 2 to 9 list {matrix {rays projectiveSpaceFan i}}

	 +------------------------+
    o3 = || -1 0 1 |              |
	 || -1 1 0 |              |
	 +------------------------+
	 || -1 1 0 0 |            |
	 || -1 0 1 0 |            |
	 || -1 0 0 1 |            |
	 +------------------------+
	 || -1 0 1 0 0 |          |
	 || -1 0 0 1 0 |          |
	 || -1 0 0 0 1 |          |
	 || -1 1 0 0 0 |          |
	 +------------------------+
	 || -1 0 0 1 0 0 |        |
	 || -1 0 0 0 1 0 |        |
	 || -1 0 0 0 0 1 |        |
	 || -1 0 1 0 0 0 |        |
	 || -1 1 0 0 0 0 |        |
	 +------------------------+
	 || -1 0 0 1 0 0 0 |      |
	 || -1 0 1 0 0 0 0 |      |
	 || -1 1 0 0 0 0 0 |      |
	 || -1 0 0 0 1 0 0 |      |
	 || -1 0 0 0 0 1 0 |      |
	 || -1 0 0 0 0 0 1 |      |
	 +------------------------+
	 || -1 0 0 0 1 0 0 0 |    |
	 || -1 0 0 1 0 0 0 0 |    |
	 || -1 0 1 0 0 0 0 0 |    |
	 || -1 0 0 0 0 1 0 0 |    |
	 || -1 0 0 0 0 0 1 0 |    |
	 || -1 0 0 0 0 0 0 1 |    |
	 || -1 1 0 0 0 0 0 0 |    |
	 +------------------------+
	 || -1 0 0 0 0 1 0 0 0 |  |
	 || -1 0 0 0 1 0 0 0 0 |  |
	 || -1 0 0 1 0 0 0 0 0 |  |
	 || -1 0 0 0 0 0 1 0 0 |  |
	 || -1 0 0 0 0 0 0 1 0 |  |
	 || -1 0 0 0 0 0 0 0 1 |  |
	 || -1 0 1 0 0 0 0 0 0 |  |
	 || -1 1 0 0 0 0 0 0 0 |  |
	 +------------------------+
	 || -1 0 0 0 0 0 1 0 0 0 ||
	 || -1 0 0 0 0 1 0 0 0 0 ||
	 || -1 0 0 0 1 0 0 0 0 0 ||
	 || -1 0 0 0 0 0 0 1 0 0 ||
	 || -1 0 0 0 0 0 0 0 1 0 ||
	 || -1 0 0 0 0 0 0 0 0 1 ||
	 || -1 0 0 1 0 0 0 0 0 0 ||
	 || -1 0 1 0 0 0 0 0 0 0 ||
	 || -1 1 0 0 0 0 0 0 0 0 ||
	 +------------------------+

After:

    i10 : netList for i from 2 to 9 list {matrix {rays projectiveSpaceFan i}}

	  +------------------------+
    o10 = || -1 0 1 |              |
	  || -1 1 0 |              |
	  +------------------------+
	  || -1 0 0 1 |            |
	  || -1 0 1 0 |            |
	  || -1 1 0 0 |            |
	  +------------------------+
	  || -1 0 0 0 1 |          |
	  || -1 0 0 1 0 |          |
	  || -1 0 1 0 0 |          |
	  || -1 1 0 0 0 |          |
	  +------------------------+
	  || -1 0 0 0 0 1 |        |
	  || -1 0 0 0 1 0 |        |
	  || -1 0 0 1 0 0 |        |
	  || -1 0 1 0 0 0 |        |
	  || -1 1 0 0 0 0 |        |
	  +------------------------+
	  || -1 0 0 0 0 0 1 |      |
	  || -1 0 0 0 0 1 0 |      |
	  || -1 0 0 0 1 0 0 |      |
	  || -1 0 0 1 0 0 0 |      |
	  || -1 0 1 0 0 0 0 |      |
	  || -1 1 0 0 0 0 0 |      |
	  +------------------------+
	  || -1 0 0 0 0 0 0 1 |    |
	  || -1 0 0 0 0 0 1 0 |    |
	  || -1 0 0 0 0 1 0 0 |    |
	  || -1 0 0 0 1 0 0 0 |    |
	  || -1 0 0 1 0 0 0 0 |    |
	  || -1 0 1 0 0 0 0 0 |    |
	  || -1 1 0 0 0 0 0 0 |    |
	  +------------------------+
	  || -1 0 0 0 0 0 0 0 1 |  |
	  || -1 0 0 0 0 0 0 1 0 |  |
	  || -1 0 0 0 0 0 1 0 0 |  |
	  || -1 0 0 0 0 1 0 0 0 |  |
	  || -1 0 0 0 1 0 0 0 0 |  |
	  || -1 0 0 1 0 0 0 0 0 |  |
	  || -1 0 1 0 0 0 0 0 0 |  |
	  || -1 1 0 0 0 0 0 0 0 |  |
	  +------------------------+
	  || -1 0 0 0 0 0 0 0 0 1 ||
	  || -1 0 0 0 0 0 0 0 1 0 ||
	  || -1 0 0 0 0 0 0 1 0 0 ||
	  || -1 0 0 0 0 0 1 0 0 0 ||
	  || -1 0 0 0 0 1 0 0 0 0 ||
	  || -1 0 0 0 1 0 0 0 0 0 ||
	  || -1 0 0 1 0 0 0 0 0 0 ||
	  || -1 0 1 0 0 0 0 0 0 0 ||
	  || -1 1 0 0 0 0 0 0 0 0 ||
	  +------------------------+