Many changes so that this python example now gives (almost) same contour plot as first plot of x09c.
Many changes so that this python example now gives (almost) same contour plot
as first plot of x09c.

svn path=/trunk/; revision=2418

FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot