cleanup for Fun.thy: merged Update.{thy|ML} into Fun.{thy|ML} moved o_def from HOL.thy to Fun.thy added Id_def to Fun.thy moved image_compose from Set.ML to Fun.ML moved o_apply and o_assoc from simpdata.ML to Fun.ML moved fun_upd_same and fun_upd_other (from Map.ML) to Fun.ML added fun_upd_twist to Fun.ML