2002-12-09 added list_empty() and hash_empty() functions
2002-09-12 fixed list_iterate function to return -1 if it gets
an invalid argument
include <config.h> and <compat.h> from source files, not
from header file, since header file is sometimes
installed as part of a user-visible API
(those APIs should eventually be redesigned without the
listhash code being publicly visible, but for now we
need to accomodate this)
2002-07-07 modified list iterate function to return int
(returns -1 if plugin function returns -1)