plbuf_image() and rdbuf_image():    save extra information    save shorts instead of PLINT/PLFLT
plbuf_image() and rdbuf_image():
   save extra information
   save shorts instead of PLINT/PLFLT

svn path=/trunk/; revision=3582

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