[Nauty] Version 2.2 beta 3 released; future things

[Brendan McKay]

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Beta 3 has these changes:

* The validation tests (make checks) work again.  They broke in
  beta 2 because the random number generator changed.

* You can run nauty and all of gtools except shortg on a PC,
  provided you install the environment djgpp.  See README for
  details.  Thanks to Guenter Sternten for helping with this.
  I will start to distribute binaries for PC when I install
  the necessary tools to make DOS binaries on my Linux box.

If you aren't having trouble with beta 2, there is no good
reason to upgrade.

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Recent versions of nauty have the in-principle capability of
processing objects other than graphs.  The same program can
even use nauty on several types of object at once.  So far
I have not released any code for this but a few bits exist
in working protypes.  Here is a list of what is planned.

1. Sparse graphs.  Presently a graph needs n^2 bits of storage
  irrespective of the number of edges, so getting past about
  60,000 vertices is nearly impossible.  This facility will allow
  you to process graphs and multigraphs up to millions of vertices
  provided they fit into memory at 16 bytes per edge.  There will
  be an option for allowing colours on the edges.

2. Hypergraphs/designs.  This facility will treat hypergraphs as
  objects of size equal to the number of points, irrespective of 
  the number of edges.  Usually it will be more efficient than
  converting the hypergraph into a bipartite graph.

3. Matrices.  This facility will treat equivalence of integer
  matrices under independent row and column permutations (and
  maybe under transpose).  An option will allow Hadamard
  equivalence, which in addition considers multiplication of
  rows and columns by -1.

Requests will be considered.

Cheers,
Brendan.