Restore default colours so that this example does not interfere with others if they are all run sequentially from same script.
Restore default colours so that this example does not interfere with
others if they are all run sequentially from same script.

svn path=/trunk/; revision=3677

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