Fix problem with wrong delta plot y-axis range when using negative y values

[marsiwiec]

When y values to be plotted are negative, the rawplot.ylim vector contains negative values, which combined with negative summary_control values give a wrong new.delta.ylim.

Fix involves appropriately reversing this vector when the absolute value of the second element is smaller than the absolute value of the first element (which for ylim vectors happens when both are negative).

[marsiwiec]

Turns out my fix misaligns the two vertical axes.

[josesho]

Thanks for this; will review and push when I can!

[marsiwiec]

Thanks for this; will review and push when I can!

Thanks!