fix B17005 - autoquiver bug

hold_another_object() will try to quiver the object being held if
it's a weapon (or gem/rock ammo) and the autoquiver option is enabled and
the quiver is empty.  It was doing that even if the object had just merged
with primary or secondary weapon, resulting in it being equipped in two
slots at once.  (Easiest way to reproduce it is via wish+wield+wish for
similar item, but it could also occur when stealing while in nymph form.)

     This also addresses one of the old items on <Someone>'s list:  if you
carry a sling equipped in the alternate weapon slot, include gems and
rocks as likely candidates for quivering same as when wielding a sling.
This extends that to autoquivering; ammo appropriate for your alternate
is now given preference over arbitrary weapons (ammo for your wielded
weapon and arbitrary missiles still take precedence over alternate ammo).

     Bug?  pickup_object() is not autoquiver aware, hence autopickup isn't
either.

     Bug too (perhaps moot if the above is changed)?  Snagging a monster's
weapon with a bullwhip uses hold_another_object() so possibly autoquivers;
snagging an object off the floor with a grappling hook uses pickup_object()
so doesn't.

doc/fixes34.1

@@ -362,6 +362,9 @@ engraving on headstone will appropriately dull your weapon
 certain types of golems should not "catch fire" so adjust the messages
 no longer need to manually examine inventory after regaining sight in order
 	to give a type name to an object picked up while blind
+when adding an object to inventory, it is possible for it to becomed both
+	wielded and quivered if it merges with weapon and autoquiver is enabled
+include rocks as likely candidates for quivering if alternate weapon is a sling
 
 
 Platform- and/or Interface-Specific Fixes