Unified the temporary file naming for images as well as vector plots so it uses...

Commit by leighsmith :: r163 /trunk/nlisp-gnuplot.lisp: (link) Unified the temporary file naming for images as well as vector plots so it uses the samecross-platform directory convention. Added window titling for images and expanded the x &y plotting range minima by 1 so small size matrices are properly displayed against the axes.