Calling it "Tracks" in most places but "Train Tracks" in others leads
to confusion.

This is that annoying feature of up-to-date 'convert' in which
converting to or from a PNG file defaults to returning RGB values that
have been 'helpfully' gamma-corrected (or some such) from the exact
data stored in the source file to some nonsense you didn't want.

Usually the worst this causes is slightly washed-out looking graphics,
but in this case, since my entire aim was to squash the image into a
specific set of exact RGB values so as to turn it into a paletted
Windows icon file, it caused an actual build failure when the next
loop in icon.pl couldn't find the gamma-corrected values in its
expected palette map, and no wonder.

It actually went off this morning, after an upgrade of ImageMagick,
and I found that it contained both unprintable characters in the
colour description and the wrong variable in the coordinate display.

Its absence was breaking the icon build on Ubuntu 14.04, because you
ask convert to map an image into a specific 16-colour palette, and it
does so and _then_ nonconsensually maps those colours in turn through
a colourspace transformation you didn't ask for, causing icon.pl to
fail an assertion when it finds an RGB value not in the palette.

Based on a web game I saw a few years ago, and dashed off this weekend
after I thought of a way to write a good (though not quite optimal)
heuristic solver, here's a random little thing not quite in the same
line as the most usual kind of Puzzles fare: instead of making you
scratch your head to find any move to make at all, it's easy to find
solutions in principle, and the challenge comes from having to do so
within a move limit.

[originally from svn r9797]
[r9795 == 3fc5a644a72e747b1f88125b38b2f178a9bc7ed3]

implementation of a puzzle usually called 'Tohu wa Vohu'.

[originally from svn r9680]