Floating-point total ordering.

Floating-point total ordering.

- (flo:total< x y) is true if x < y in the total ordering on
  floating-point values defined in IEEE 754-2008 Sec. 5.10, i.e. this
  is the totalOrder function of IEEE 754-2008 Sec. 5.7.2.
- (flo:total-order x y) is -1 if x < y, 0 if x = y, +1 if x > y in the
  total ordering -- the three-way comparison version of total<.
- (flo:total-mag< x y) = (flo:total< (flo:abs x) (flo:abs y))
- (flo:total-order-mag x y)
  = (flo:total-order (flo:abs x) (flo:abs y))

While here, tweak release notes on flonum stuff.