Fix KGlobalSettings::createApplicationPalette to Do The Right Thing (i.e. use KColorScheme states). Color accessors in KGS are now even-more-deprecated because they are now "wrong" as well, but they use the new ctor so that kglobalsettings.cpp doesn't generate warnings about using the now-deprecated KColorScheme ctor. (Also make the @deprecated doc for said accessors more detailed.)