bug in plots made with PLOT/STEP=CONNECTED

[ACManke]

I think this has been in the code for a long time. I can see it in classic-Ferret v7.6; it seems that PLOT/STEP and PLOT/STEP=CONNECTED are not heavily used.

! Define a synthetic variable
let var = {1,3,5,4,3,6,1}

set view ul
! A regular line plot is fine.
plot/line/sym=boxfill var
pause

set view ur
! This is wrong - the x-axis is too short
plot/step=connected var
pause

set view ll
! As an overlay, it works correctly
plot/line/sym=boxfill/siz=0.2 var
plot/step=connected/over var

When setting up to draw the step-style plot, the data is duplicated and the data sent to be plotted has a new independent axis with points between the original coordinates. It seems that the updated size of the list of data to plot is not sent to the plot routine

[ACManke]

This is fixed in plot_set_up.F