Set the stroke width to 1.0 in filled_polygon() - shade plots without transparency look ok with this setting. 
Set the stroke width to 1.0 in filled_polygon() - shade plots without transparency look ok with this setting. 

svn path=/trunk/; revision=8997

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