io.encodings.utf32: Fix unmatched <PRIVATE.
basis: End <PRIVATE with PRIVATE>.
sequences: Add some short useful factors. Clean up the use of longest.
zoneinfo: Add helper words.
zoneinfo: Update files.
sequences: More efficient longest and shortest by moving infimum-by/supremum-by into core.
sequences, tetris, rosetta-code: Simplify some code.
hash-sets: use ?adjoin instead of (all-unique?).
words: add safety checks for word? type.