[install] Add gnuplot pkgs (Fix #132, thanks to http://askubuntu.com/questions/277363/gnuplot-not-showing-the-graph-window).
[install] Add gnuplot pkgs (Fix #132, thanks to http://askubuntu.com/questions/277363/gnuplot-not-showing-the-graph-window).

130s/hut_10sqft,130s/hut_10sqft,130s/compenv_ubuntu,130s/compenv_ubuntu