Some cleanup code at exit moved into plserver.c, and the exit_app proc was eliminated (in favor of just exit).
Some cleanup code at exit moved into plserver.c, and the exit_app proc was
eliminated (in favor of just exit).

svn path=/trunk/; revision=1352

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