Accessibility: lookaround command, mention_map option

Adds a new extended command #lookaround, which will describe
the map around the hero they can see or remember.

Adds a new boolean option mention_map, which will give a message
when an interesting map location in sight changes.

include/flag.h

@@ -194,6 +194,7 @@ struct accessibility_data {
     boolean mon_notices;   /* msg when hero notices a monster */
     int mon_notices_blocked; /* temp disable mon_notices */
     boolean mon_movement;  /* msg when hero sees monster move */
+    boolean glyph_updates; /* msg when map glyphs change */
 };
 
 /* Use notice_mon_off() / notice_mon_on() to temporarily disable