Modification of *-time tests so that they don't break if the test was skipped.

Modification of *-time tests so that they don't break if the test was skipped.

Now it checks and attempts to create symbolic links only if the directory it works from isn't empty.
(When it is, calling "ln -s ../somedir/*.txt ." creates broken link named *.txt and plot.sh,
 so the plotting script attempts to create a plot, which fails and stops the rest of the plotting from happening.)