Contract 9.7.0

A new tool, battles_deck_upgrades: the other half of a war set, "what should I upgrade so my four decks get better". It starts from the player's best set of decks sharing no card today (the candidates, values and exact packing of battles_deck_sets) and prices two things by re-packing the set: single upgrades (a card raised toward the level the player fields, at most max_levels at a time, or an Evolution or Hero form unlocked that a candidate deck plays), and within_reach, the decks outside the set that would join it once each of their low cards reaches that level. Each says the set's value before and after (gain, in the same log-odds battles_deck_sets optimises), the levels it takes and the set it would give. Levels, not gold: the game's upgrade costs are not in the record.

• battles_deck_upgrades: options (kind level or form), within_reach (raises, forms, levels), baseline.

Additive.