am 77ea834d: am d989a8e3: Added check for the version of Gnuplot.

Merge commit '77ea834dd18533b9e75ba0c5b3f6f38547e0ff97'

* commit '77ea834dd18533b9e75ba0c5b3f6f38547e0ff97':
  Added check for the version of Gnuplot.