wishing tweak: detect X vs X detection (trunk only)

wishing tweak: detect X vs X detection (trunk only)

     Allow wishing for a "potion of detect objects" to generate a
"potion of object detection", or for a "spellbook of monster detection"
to generate a "spellbook of detect monsters".

     To get a spellbook you'll need to explicitly specify "spellbook"
even when using a name that's unique to books:  asking for "detect food"
will yield a "scroll of food detection" rather than "spellbook of detect
food" because it finds potions and scrolls first.  [That's nothing new
for the case where a spellbook and potion or scroll have the same name,
only new behavior for "detect X" vs "X detection" matches.]

     Wishing for "detect food" used to yield a random food item rather
than a "spellbook of detect food".  That's fixed now, although as
mentioned above it will actually produce a "scroll of food detection".