Confused #loot (trunk only)

Attempting to loot while suffering from confusion and not on top
of a container will drop gold if hero is carrying some, but it behaved
differently for GOLDOBJ config (gold dropped over a hole or down stairs
always stayed on current level) than for !GOLDOBJ (gold had a chance to
fall to lower level) when done at some location other than a throne.
This makes GOLDOBJ use dropx() instead of dropy(), same as !GOLDOBJ.

     And with access to a throne it can be used to repeatedly summon
monsters until they're extinct.  This makes it check for confusion before
finding containers, but the chest/exchequer code doesn't always kick in
so can't be attempted as many times before confusion expires, throttling
summoning a little.  Also, when placing hero's gold into a chest, it now
clears the contents-known flag and relocks the chest.

doc/fixes35.0

@@ -30,6 +30,7 @@ class genocide recognizes species name as an example of the class to
 internals: use Is_box rather than explicitly checking what it checks
 fix some unreachable messages (either make then reachable or remove them)
 can quiver coins when GOLDOBJ is defined
+make #loot behave same for GOLDOBJ as for !GOLDOBJ
 grammar, spelling and other typos
 keep various delayed killers separate to avoid mixed up messages
 don't place randomly-placed aquatic monsters in lava on special levels