Added new ThresholdPlayers file, with FixedThreshold player class.  Added bot players to game that weren't previously being used: FairHunter, AverageHunter, BoundedHunter.
Command-line arguments: Removed one of the new ones, --log-to-file.  Can use presence or absence of the log file name argument to determine whether to output to a file or not.  Also, rather than specifying an output stream in each print statement, easier to redirect stdout to output to a file during initialization of the Game object.
Log detailed information about each contest a player takes part in, in every round, if do_logged is passed into player class constructor.