math.polynomials: add test for negative p^.
math.matrices: add error for negative m^n (and test).
sequences.extras: use either?.
use swapd in a few places.
hashtables: use >= in hash-large?.
hash-sets: use >= in hash-large?.
math: fix quot stack effect in unless-zero.
hash-sets: simplify <hash-set>.
hashtables: simplify <hashtable>.
compiler.tree.propagation.transforms: previous H{ } and HS{ } optimization no longer necessary.
sequences: change trim-head to not call length unless it needs to.
sequences: cleanup docs for tail.
growable: improve docs for ensure.
sorting.extras: adding in-place insorts.
sequences.extras: remove insert-sorted (can use versions in sorting.extras instead).