v0.1.0

• Initial development: the PHPStan extension of the understudy family.
  Matchers are typed never so one may stand in for a declared parameter at
  level 9 and above without a single diagnostic being suppressed; when()
  and expect() get the builder type they really produce, so returns() and
  answers() are checked against the method being specified;
  Understudy::wire() gets the shape read off the constructor; and five
  rules report specifications that cannot work — understudy.closure,
  understudy.cardinality, understudy.matcher, understudy.returns and
  understudy.matcherLeak.