function, since it took no parameters by which to vary its decision,
and in any case it's hard to imagine a game which only
_conditionally_ wants a status bar. Changed it into a boolean data
field in the backend structure.
[originally from svn r6417]
was actually using it, and also it wasn't being called again for
different game states or different game parameters, so it would have
been a mistake to depend on anything in that game state. Games are
now expected to commit in advance to a single fixed list of all the
colours they will ever need, which was the case in practice already
and simplifies any later port to a colour-poor platform. Also this
change has removed a lot of unnecessary faff from midend_colours().
[originally from svn r6416]
