Connect gnuplot_x11 to exterior application window

[Daniel J S. <dan...@ie...>]

I've updated the patch, 1027032, for connecting to the external X11 window against the most recent CVS version.  [Is SourceForge updating the CVS version... the last update seems over a week ago and there is a bug.]

This left off where Ethan couldn't get the TCL demo to run on his system.  Ethan, please give it a try and let me know if it is work.

The amount of extra code is actually small but the patch is big because "plot" is changed to "current_plot" in a lot of places.  I'd propose if this is added to CVS I go back and simply get rid of the EXPERIMENTAL option of "--disable-external-x11-window".  It would simply be bloating CVS with a bunch of conditionals for slightly different code.

Dan