* Add partner swap party mode
A new party mode for 3 to 12 players that only needs 2 microphones. Everyone plays for themselves, but always sings together with a partner. Both singers get the score of the pair, and the partners change every round.
- In each round every player sings once, with a partner they haven't sung with yet; with an odd number of players someone takes a break, in turns
- Ranking by the average score per song, so breaks are no disadvantage
- Optional harmony bonus of 500 points when both singers are no more than 500 points apart
- Duet songs are sung with both voices; duets can be mixed in, used exclusively or left out
- Up to 3 jokers per player to skip a song
- The best pair is shown all the time, and the winner and the best pair of the night are celebrated at the end
* Rename the harmony bonus points constant to avoid shadowing
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Co-authored-by: Florian Ostertag <flokuep@users.noreply.github.com>
