Code to construct Windows icon files for the puzzles, by munging the
screenshots into appropriate sizes and colour depths. This is all
done with a nasty Perl script, because ImageMagick does not output
correct .ICO format. Not sure why; it isn't _that_ hard.

I intend at some point to link the resulting icons into the actual
Windows puzzle binaries, but before then I have to make them
prettier: most of them would benefit from being derived from a
smaller crop of the puzzle screenshot instead of trying to fit the
whole thing in.

[originally from svn r7017]