Actually works now.  Makes three plots, shading a single or multiple regions.
Actually works now.  Makes three plots, shading a single or multiple
regions.

svn path=/trunk/; revision=441

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