Log Message:
py-gnuplot-1.8:

* hardcopy allows for terminal='svg' (using a patch from Spyros Blanas)

* Use with_ instead of with as that will be a python keyword in the
  future.

* Added an option "filename" to Data and GridData in PlotItems.py.
  This allows saving the data to a permanent, rather than temporary,
  file.  (Patch contributed by Matthew Fulmer.)

* Added a 'pdf' terminal definition (using a patch from Jim Kleckner).

* Added close() and __del__() methods to the Gnuplot class.  This
  might help with some cases of premature temporary file deletion.
  (Suggested by Jim Kleckner.)