Independent side now visible if necessary

[Hans Ronne]

I have checked in code that makes the independent side show up by default
in the tcltk player setup dialog when it is played by a human or AI player
(this would of course only happen with saved games).

More importantly, the independent side will now also show up in the tcltk
side list if it has a player. With the old code, it would not show up even
if you played it yourself, which was kind of strange. This change also
makes the interfaces more similar since the Mac interface has worked this
way for a long time.

Hans