Added bop_handler and eop_handler function pointers & client data pointers.
Added bop_handler and eop_handler function pointers & client data pointers.

svn path=/trunk/; revision=3553

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