present() - find an object by id
object present( mixed str, object ob );
if first argument is string, second argument is missing, searches for
a object in the object's environment using the id() apply where it answers 1
to indicate a match.
if first argument is string, second argument is object, only searches
for target in that object's inventory using the same strategy as above.
"foo 1" means the first "foo" in the inventory. the first in the
inventory is the last object that moved in.
if first argument is object, second argument is missing, check if
object is in this object's inventory, or as a sibling in this object's
environment's inventory, returns object's parent.
if first argument is object, second argument is object, check if
object1 is in object2 inventory, return object1 if true.
If object is hidden (via set_hide()), and current object is not hid‐
able. returns 0