Improve challenge party mode (#911)

- Instead of a number of rounds, you now choose how many songs each player sings
- New option to remember sung songs, so a new challenge doesn't repeat songs from the previous ones
- Up to 16 players
- The number of jokers and the joker refill setting are kept instead of being reset every time
- The overview shows each player's avatar, the top three in gold, silver and bronze and highlights the leader
- The winner of each round is highlighted in the round list
- The winner is celebrated at the end with avatar, a pulsing gold name and stars

Co-authored-by: Florian Ostertag <flokuep@users.noreply.github.com>

Output/PartyModes/Challenge/Languages/en.xml

@@ -18,6 +18,8 @@
   <string name="TR_SCREENCONFIG_NUMROUNDS">Number of rounds</string>
   <string name="TR_SCREENCONFIG_NUMJOKERS">Number of jokers</string>
   <string name="TR_SCREENCONFIG_REFILLJOKERS">Refill jokers every round</string>
+  <string name="TR_SCREENCONFIG_SONGSPERPLAYER">Songs per player</string>
+  <string name="TR_SCREENCONFIG_REMEMBERSONGS">Remember sung songs</string>
   <string name="TR_SCREENNAMES_TITLE">Challenge Mode: Choose Player</string>
   <string name="TR_SCREENNAMES_BUTTON_RANDOM">Select random</string>
   <string name="TR_SCREENMAIN_TITLE">Challenge Mode: Overview</string>