detection revamp

detection revamp

Change most instances of detection to offer the player a chance to
move the cursor around on the map so that the getpos() autodescribe
feature can explain things that might go away as soon as the
current detection completes.  The few instances that don't offer
such a chance are the ones where everything which has been revealed
will still be there once the action finishes (such as regular magic
mapping and blessed/persistent monster detection).

There were quite a lot of inconsistencies in things like handling
for detection while swallowed or underwater.  I didn't keep track
of them to distinguish between 3.6.0, current dev code, or my patch
in progess.  They should be much more consistent now but without a
comprehensive fixes36.1 entry.

Blessed clairvoyance (divination spells at skilled or expert) now
shows monsters as well as terrain.  I first had it like that for
any clairvoyance, but having getpos/autodescribe kick in every 15
or 30 turns once you have the amulet--or pay the appropriate amount
to a temple preist--was nearly unplayable.  When it only follows an
explicit spell cast it is not intrusive.