#24 y_right_format y2_format

[subaqua]

Sometimes we have widgets on the left y-axis and dollars on the right y-axis and we'd like to specify different axis format strings for each set.

At this point in time we can use set_y_format() but that changes the right y-axis as well which doesn't work for our graphs where the unit types are different.

This would be a useful feature.

Thanks for all your great work.