Added a `--generate' command-line option in the GTK port of every

puzzle, to make it construcct puzzle IDs and output them on stdout.
Also checked in print.py, a script which reads puzzle IDs on stdin
and produces PostScript output. With these, you can generate pages
of Pattern, Rectangles and Solo puzzles to take on trains with you.

git-svn-id: svn://svn.tartarus.org/sgt/puzzles@5707 cda61777-01e9-0310-a592-d414129be87e