Hero remembers trapped boxes

After finding a trap on a chest or a large box, remember it
as trapped: "You see here a trapped large box."
Randomly generated chests and boxes can be obviously trapped.
Allow defining obviously trapped containers via lua.

Invalidates saves and bones.

src/objnam.c

@@ -1334,6 +1334,9 @@ doname_base(
             Strcat(prefix, "uncursed ");
     }
 
+    /* "a large trapped box" would perhaps be more correct */
+    if (Is_box(obj) && obj->otrapped && obj->tknown && obj->dknown)
+        Strcat(prefix,"trapped ");
     if (lknown && Is_box(obj)) {
         if (obj->obroken)
             /* 3.6.0 used "unlockable" here but that could be misunderstood