merged;

updated versions

added component integrity checks and some initial checksums

prefer canonical fold_rev;

back to naive insertion sort before 1997 to accommodate peculiar less_arg relation -- NB: make_ord arg_less was not a quasi-order and thus inappropriate for generic sort (cf. de74b549f976, ecfeff48bf0c);

tuned proof;

more precise imports;

removed some old/unused stuff;
tuned whitespace;

actually remove former atbroy102/cygwin stuff (cf. 6301046146b6, 08cb859c53cd);

more user aliases;