Revisit sort order

[HighDiceRoller]

Originally I had wanted to put everything in ascending order. However, this clashes with the natural ordering of several evaluators.

Favoring ascending order:

• die.outcomes()
• Default evaluator order. For mixed standard dice this allows for more favorable caching.

Favoring descending order:

• Sizes of matching sets and straights.
• Compair, since RISK uses descending order.

Debatable:

• pool.keep() and pool[].

In favor of ascending:

• Follows Python's default.
• Non-negative indexes = ascending and negative indexes = descending is natural.
  • There is a reverse argument for negative = lowest and non-negative = highest, however, I think this argument is weaker.

In favor of descending:

• Used by AnyDice. (Though AnyDice is also 1-indexed...)
• Most games favor higher dice.

• pool.expand()

Ascending looks more natural to me.

Descending plays better with lexicographic ordering.

[HighDiceRoller]

Decision: add order option to expand(), but the two debatables stay on ascending.