@CHOWN (thing|#nnn) = (ME|[*]player|[+]group)
Changes the ownership of (object) to (player/group).
Players may chown 'unwanted' objects they can 'use' to themselves.
(i.e., If a player @locks a gift to a friend and then sets it unwanted,
the recipient can later @chown it to him/her/itself.)
@CHOWNing a (thing) to a (group) will give the members of the (group)
control over the (thing). (group) must be set LINK_OK if not owned
by the player performing the @CHOWN.
Players can't be chowned; they always own themselves.