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.

win/curses/cursmain.c

@@ -126,8 +126,6 @@ struct window_procs curses_procs = {
 #endif
     curses_get_color_string,
 #endif
-    curses_start_screen,
-    curses_end_screen,
     genl_outrip,
     curses_preference_update,
     curses_getmsghistory,
@@ -1207,27 +1205,6 @@ curses_delay_output(void)
 #endif
 }
 
-/*
-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
-curses_start_screen(void)
-{
-}
-
-/*
-end_screen()    -- Only used on Unix tty ports, but must be declared for
-               completeness.  The complement of start_screen().
-*/
-void
-curses_end_screen(void)
-{
-}
-
 /*
 outrip(winid, int)
                 -- The tombstone code.  We use genl_outrip() from rip.c