Check for nan (not a number) values in plcol1 to avoid potential segfaults
Check for nan (not a number) values in plcol1 to avoid potential segfaults

svn path=/trunk/; revision=10450

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