B06005 - cancelling getdir prompt

- Changed a cancelled chat direction to abort the chat -- it seemed odd
that the old behavior would sometimes take time, sometimes not, depending
on the previous direction.
- Documented the current spelleffects behavior of re-using the last
direction after a cancelled getdir() & added a message.

src/sounds.c

@@ -860,7 +860,10 @@ dochat()
 	return(1);
     }
 
-    (void) getdir("Talk to whom? (in what direction)");
+    if (!getdir("Talk to whom? (in what direction)")) {
+	/* decided not to chat */
+	return(0);
+    }
 
 #ifdef STEED
     if (u.usteed && u.dz > 0)