Add notes to README.release on support for NaN / Inf values to some  plotting routines.
Add notes to README.release on support for NaN / Inf values to some 
plotting routines.



svn path=/trunk/; revision=9834

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