Make Y-axis order auto-adjust based on values

[LesleyAtwood]

We want to response variable group order to automatically adjust so that the group that contains a point with the most positive value (or mean value of all points on the line?) rises to the top of the list and the group with the most negative value (or mean value of all points on the line?) drops to the bottom of the list.

Group orders currently reorder when only one point/line is displayed, but does not work when there is more than one point/line.