Revision history for Perl extension GnuplotIF.

1.0  Thu Jul 28 11:00:14 2005
  - original version; created by h2xs 1.23 with options
  -XA -n GnuplotIF

1.1  Aug 27 2006
  - method gnuplot_set_plot_titles added (thanks to Stephen Marshall)

1.2  Jun 06 2007
  - tests improved

1.3  Oct 13 2007
  - Module no longer dies if no display is available (allows batch mode). 
  - Method gnuplot_plot_xy_style (thanks to Georg Bauhaus)

1.3.1  Nov 10 2007
  - All prints to pipes will be checked.
  - New test: 8 pipes open in parallel.

1.4  Nov 28 2007
  - Plot window can survive after gnuplot exits.
  - Plot can be stored to a script file instead of beeing executed immediately.
  - New method gnuplot_plot_3d makes 3-D-plots from arrays.
  - New method gnuplot_hardcopy writes a plot into a file for printing.
  - New method gnuplot_restore_terminal restores terminal settings before the last hardcopy.