Use negative numbers in range to make sure bounding-box calculation is still good for that.  (It was.)
Use negative numbers in range to make sure bounding-box calculation is
still good for that.  (It was.)

svn path=/trunk/; revision=11806

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