Changes from nauty 2.4 to nauty 2.5
-----------------------------------

* Add Traces.  The main files are traces.h and traces.c, but
  many changes were made to dreadnaut.c and nausparse.c also.

* Allow thread-safe storage if requested by configure --enable-tls
  and available.  This allows parallel running of nauty and Traces
  in separate threads.

* The makefile now creates static libraries like nauty.a in 
  addition to object files like nauty.o.

* Remove all use of types permutation, nvector, np2vector, shortish.
  These are now int.

* Add schreier.h, schreier.c and the optional use of the random
  Schreier method in nauty.  These are also used in Traces, but
  are not optional there.

* Add large-file support to all programs, assuming it is available.
  Now there is no longer a 4GB limit on files read or written on
  32-bit systems.

* Use gcc extensions like __builtin_clz() if available and not
    disabled by configure --disable-clz.
  Use FIRSTBITNZ instead of FIRSTBIT if the argument is certain
    to be nonzero.

* New macros defined in nauty.h:
   COUNTER_FMT
   PRINT_COUNTER
   SETWORDSNEEDED
   ADDONEARC
   ADDONEEDGE
   EMPTYGRAPH

* The options structure has a new boolean field schreier.

* New procedures:
  densenauty()  in naugraph.c  - simplified dense graph interface
  sparsenauty() in nausparse.c - simplified sparse graph interface
  writegroupsize() in nautil.c - write two part group size
  copy_sg() in nausparse.c     - make a copy of a sparse graph

  densenauty() and sparsenauty() are now the recommended ways to
  call nauty from a program.  See the sample programs in the package.

* Use quicksort in place of shell sort in many places.  This is 
  implemented in the file sorttemplates.c that can be used in any
  applications.

* Apply the const attribute more liberally across the code.

* The sparsegraph fields nde and *v changed type from int to size_t.
  This is to allow more than 2^31 edges on 64-bit hardware.

* sparsegraph.h and sparsegraph.c:
    Corrected definition of SG_DECL in sparsegraph.h. (The erroneous
       definition would have worked but generated warnings.)
    Added DEFAULTOPTIONS_SPARSEDIGRAPH.
    Added comparelab_tr(), testcanlab_tr(), updatecan_tr() for Traces.

* gtools.h and gtools.c:
    Now gtools.h is made from gtools-h.in by configure.
    Updated G6LEN() to work for larger graphs.
    Use large-file functions fseeko(), ftello() if possible.

* Most tools now use the random number generator in naurng.c rather
  than that in rng.c.

* gutils.h, gutil1.c and gutil2.c:
    New procedures maxcliques(), indpathcount1(), indcyclecount1(),
      indcyclecount().

* Invariants:
    Corrected getbigcells(), making a small change to invariants
       celltrips, cellquins and refinvar.

* dreadnaut:
    Sparse nauty and Traces now incorported.
    New commands: A, G, F, FF, sr, O, OO, P, PP, S, V
    w command is now in units of 2*m.
    Command-line can run commands using -o.
    M command is extended; now applies to i as well as x.
    Implement ANSI controls if requested.
    File names for > and < can be given in "..." to allow spaces.
 
* Updates to utilities:
     listg:  add -b (Bliss format), -G (GRAPE format) and
          -y/-Y (dotty format), -H (HCP format)
     labelg: add -t (Traces) and -i16 (refinvar)
     countg/pickg: add -m (vertices of min degree),
         -M (vertices of max degree), -H (induced cycles),
         -K (number of maximal independent sets)
     genrang: add -t (tree)
     genbg: add -A (antichain)
        The makefile can also make genbgL which makes larger sizes
     directg: add PROCESS feature
     shortg: -S (use sparse nauty), -t (use traces), i16 (refinvar)

* New utilities:
     ranlabg: randomly relabel graphs
     linegraphg: compute linegraphs
     subdivideg: compute subdivision graphs
     watercluster2: orient edges of graphs (by Gunnar Brinkmann)

* Version 25r2 fixed a rare error in Traces
  Version 25r3 fixed some problems in the configure script (thanks to Daniel Grayson)
  Version 25r4 fixed another rare error in Traces