v0.91.0

Added

• verdict: the vocabulary every decision point shares when it decides
  whether an automated action runs. Allow, Flag, Ask and Block
  in their order; Least, under which a verdict outside the four counts
  as Block, so composition only narrows; OnFailure, which is never
  more permissive than Ask; and Decide, which applies a ceiling and
  random review sampling to a suggested verdict and returns the verdict
  with the probability, fixed before the action runs, that a person sees
  it. Recording that probability with each decision is what lets any
  decision source's error rate be estimated without bias. A harness that
  ranks verdicts itself should move to Least: ranking an unknown
  verdict by its index in a list makes it the most permissive.