[Retros] Natch-3.0-beta1 is out. Correction of a bug.

[Pascal Wassong]

Hello all,

Dominique Forlot found a bug in the beta version of Natch.  Some
solution where not found in a special case.  Here is a SPG that is not
solved by natch-3.0-beta.

1.a4 b5 2.axb5 Bb7 3.Rxa7 Bc6 4.Ra1 Ra2 5.b3 Rb2 6.Ra8

The bug involved:
- the conflict of trajectories of the rooks.
- the capture of the pawn at its home square.
- the presence of a spare move (because Natch doesn't find that the rook
  must make a switchback to open the column to the other rook).

The bug is now corrected in the version Natch-3.0-beta1, which is
available at the usual place: http://Natch.free.fr/Natch.html

Have fun composing !
Pascal