v0.2.8

• portfolio has the option hashes. The default all keeps the behavior of 0.2.7.
• With hashes: "pick", the members get no output hash before the pick. Only member 0 and the winner get a hash, when the winner is not member 0.
• The output hash is most of the key cost of a member. selectBest does not use it, so the winner and picked do not change.
• Under pick, a hash that throws makes pick throw a RangeError. Only the hashed traces have an outputHash.
• A value of hashes that is not all or pick causes a RangeError. docs/PORTFOLIO.md tells the rules.