plbuf_image() and rdbuf_image(), use correct size of X/Y matrices.
plbuf_image() and rdbuf_image(), use correct size of X/Y matrices.

svn path=/trunk/; revision=3426

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