unhiding during level change

unhiding during level change

     From the newsgroup:  if a pet was hiding under an object next to you
when you changed levels, it could arrive hidden at the destination if there
was something available to hide under there too, and sometimes you'd start
the new level with a hidden monster glyph at its location.  I was able to
reproduce that once with current trunk code, but while trying to figure
out what is actually happening I've been unable to make it happen again.
However, it doesn't make sense for a monster to be able to remain in hiding
during the level change in the first place, so this patch prevents that.
(I'd still like to know how/why map_invisible() is sometimes getting called.
[The test character was a level 1 tourist without auto-search capability.]
I'm reasonably sure that it won't happen any more once this fix in place.)

     This also brings adjacent pets out of hiding when they accompany you
during ascension or dungeon escape, but it seems that that wasn't actually
necessary.  The end of game disclosure already lists such by name rather
than as "it", contrary to my expectations.  (I had forgotten that end-of-
game forces true names so that blindness and hallucination don't interfere
with disclosure; obviously that ends up handling hidden monsters too.)