Update to version 4.0. Provide support for

Update to version 4.0.  Provide support for
EDT scroll margins at top and bottom of the window.  Provide an
emulation of the EDT SUBS command (bound to GOLD-Enter, by
default).  Enhance edt-quit, bound to GOLD-q by default, to warn
user when file-related buffer modifications exist.  Provide
support for running EDT Emulation in XEmacs.  Provide customize
access to some user updatable variables.  Add Commentary section
to file header.  Fixed a few minor bugs and cleaned up some code.