eliminated odd comment from distant past;

updated cut_tac, without loose references to implementation manual;

updated generated file;

simplified cut_tac (cf. d549b5b0f344);

merged

avoid using constant Int.neg

reactivated Find_Unused_Assms_Examples to avoid untested / dead stuff in the repository; moved the whole HOL-Quickcheck_Examples target from "all" to "full" for now -- it does not terminate in certain situations (to be investigated further);