window-port updates

Remove start_screen() and end_screen() from the
Window-port interface.

They were only ever used by tty, and there was a comment
carried to several window-ports about how they "really
should go away. They are tty-specific"

term_start_screen() and term_end_screen() are part of
terminal/NO_TERMS supporting routines now.

outdated/win/gnome/gnbind.c

@@ -44,8 +44,7 @@ struct window_procs Gnome_procs = {
 #ifdef CHANGE_COLOR /* only a Mac option currently */
     donull, donull,
 #endif
-    /* other defs that really should go away (they're tty specific) */
-    gnome_start_screen, gnome_end_screen, gnome_outrip,
+    gnome_outrip,
     genl_preference_update, genl_getmsghistory, genl_putmsghistory,
     genl_status_init, genl_status_finish, genl_status_enablefield,
     genl_status_update,
@@ -1132,29 +1131,6 @@ gnome_delay_output()
     }
 }
 
-/*
-start_screen()  -- Only used on Unix tty ports, but must be declared for
-               completeness.  Sets up the tty to work in full-screen
-               graphics mode.  Look at win/tty/termcap.c for an
-               example.  If your window-port does not need this function
-               just declare an empty function.
-*/
-void
-gnome_start_screen()
-{
-    /* Do Nothing */
-}
-
-/*
-end_screen()    -- Only used on Unix tty ports, but must be declared for
-               completeness.  The complement of start_screen().
-*/
-void
-gnome_end_screen()
-{
-    /* Do Nothing */
-}
-
 /*
 outrip(winid, int, when)
             -- The tombstone code.  If you want the traditional code use