[gnuplot] Choosing line type and color in Gnuplot 4.0

Here is the syntax:

  set terminal pdf {monochrome|color|colour}
                   {{no}enhanced}
                   {fname "<font>"} {fsize <fontsize>}
                   {font "<fontname>{,<fontsize>}"}
                   {linewidth <lw>} {rounded|butt}
                   {solid|dashed} {dl <dashlength>}}
                   {size <XX>{unit},<YY>{unit}}

and an example:

set terminal pdfcairo monochrome enhanced font "Times-New-Roman,12" dashed