Fair playing time and substitution groups

The AI planner now splits playing time evenly and keeps linked players together on the pitch.

The substitution planner has been rebuilt: apart from the keeper, every player now gets as close to exactly equal minutes as possible. When perfect equality is not possible, you get advice on the best number of substitution moments.

New: substitution groups. Group your defenders (or any block) and set how many of them must always stay on the pitch. The planner and AI lineup respect that rule.