Return empty brush/pen/font via API rather than the weird default one Previously a non-initialized QPen()/QBrush()/QFont() was returned if axis/series hadn't been added to a chart yet and therefore had not been themed yet. To keep API somewhat consistent with old behavior, return non-initialized QPen()/QBrush()/QFont() instead of the weird default one in these cases. The new behavior is slightly different in that it is no longer possible to restore themed behavior by setting pen/brush/font to non-initialized one, but since there is no way to differentiate e.g. legitimate Qt::black pen from non-initialized pen, we can no longer support this behavior. Change-Id: I99f3d8853b329b5345e3073c040d8bfa8b9b75b4 Reviewed-by: Tomi Korpipää <tomi.korpipaa@digia.com>