message: inline action to hash
diff: @@ -56,7 +56,7 @@ struct ActionHasher : public boost::static_visitor<std::size_t>
  std::size_t operator()(const Input& x) const { return std::size_t(); }
  };
  -ActionHash ActionToHash(const Action& action) {
  +inline ActionHash ActionToHash(const Action& action) {
  return boost::apply_visitor(ActionHasher(), action);
  }
  