Code review comment for lp://staging/~widelands-dev/widelands/game_end_summary

Some more comments here. I also changed some style and nits around. Also you forgot to check in logic/playersmanager.[h|cc]. I also think the file should be called players_manager.h and the class PlayersManager (though we are not very consistent about this either - we definitely should do a bunch of style cleanups throughout the code base).