#5 Style 13 is broken

[Richard Archer]

Sometimes pieces show up in the wrong colour in Style
13. This is a shame, as it's my favorite style for telnet.

I'd also like to implement a style 14 which uses the
same colour
coding as style 13, but which has square squares, not
the oblongs that style 13 has.

This is a low priority, as I would guess close to
nobody uses this
style. Nevertheless, it's a bug, and you know how I
hate bugs!