TTY: Add menu_overlay option

This was a request from a blind player.  It's hard to find
the left edge of the menu when it's drawn on the map, so
clear the screen and align menus to the left edge of the screen
when this option is turned off.

Originally this was called the window edge patch.

src/options.c

@@ -149,6 +149,11 @@ static struct Bool_Opt {
     /* for menu debugging only*/
     { "menu_tab_sep", &iflags.menu_tab_sep, FALSE, SET_IN_WIZGAME },
     { "menu_objsyms", &iflags.menu_head_objsym, FALSE, SET_IN_GAME },
+#ifdef TTY_GRAPHICS
+    { "menu_overlay", &iflags.menu_overlay, TRUE, SET_IN_GAME },
+#else
+    { "menu_overlay", (boolean *) 0, FALSE, SET_IN_FILE },
+#endif
     { "mouse_support", &iflags.wc_mouse_support, TRUE, DISP_IN_GAME }, /*WC*/
 #ifdef NEWS
     { "news", &iflags.news, TRUE, DISP_IN_GAME },