Change opening message

Closes #300.
Diadem of the demon lord tweaks

It's not really a necklace. Also, the mistress is fun, so I'm increasing
the probability of her appearing.
Mausoleum synonym

Strictly speaking, the mausoleum and the tomb are not the same. But I
think this makes sense.
Recovering from blindness prose

Add a check to see whether the main actor is still in the same location
as the player. In rare circumstances this is needed (e.g., when Isra is
the main actor, and Israfel reforms, Isra will still be conscious but
not in the same location).