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/shim/winshim.c

@@ -159,8 +159,6 @@ DECLCB(short, set_shim_font_name,(winid window_type, char *font_name),"2is", A2P
 DECLCB(char *,shim_get_color_string,(void),"sv")
 
 /* other defs that really should go away (they're tty specific) */
-VDECLCB(shim_start_screen, (void), "v")
-VDECLCB(shim_end_screen, (void), "v")
 VDECLCB(shim_preference_update, (const char *pref), "vp", P2V pref)
 DECLCB(char *,shim_getmsghistory, (boolean init), "sb", A2P init)
 VDECLCB(shim_putmsghistory, (const char *msg, boolean restoring_msghist), "vsb", P2V msg, A2P restoring_msghist)
@@ -247,8 +245,7 @@ struct window_procs shim_procs = {
     shim_get_color_string,
 #endif
 
-    /* other defs that really should go away (they're tty specific) */
-    shim_start_screen, shim_end_screen, genl_outrip,
+    genl_outrip,
     shim_preference_update,
     shim_getmsghistory, shim_putmsghistory,
     shim_status_init,