* removes #perfect_score and associated specs
* removes #percentage_off
* removes percentage_off line from #score
* removes abortive Round class
removes @prev variable
removes @master_combos - old technique, not implemented
adds memoization comment to #refresh_score
changes attr_accessors to attr_readers
adds comments to #initialize, removes old commented-out code
adds more comments
removes #look_ahead, #top_rated, #score_teams and sample_student
removes specs for look_ahead and score_teams