Added procs to handle communication link.  plserver_link_init gets invoked automatically when plserver is started by the Tcl/TK/DP driver. plserver_start is used when running plserver in stand-alone mode.
Added procs to handle communication link.  plserver_link_init gets invoked
automatically when plserver is started by the Tcl/TK/DP driver.
plserver_start is used when running plserver in stand-alone mode.

svn path=/trunk/; revision=659

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