Added gcw_use_fast_rendering() to prototypes, and use_fast_rendering to GcwPLdev struct.
Added gcw_use_fast_rendering() to prototypes, and use_fast_rendering to GcwPLdev struct.

svn path=/trunk/; revision=6037

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