Include float.h, so that the definition of  PLFLT_MAX/ PLFLT_MIN works.
Include float.h, so that the definition of  PLFLT_MAX/ PLFLT_MIN works.

svn path=/trunk/; revision=4503

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