removed unused import statements in Race and RaceAbstract and updated comments. Changed event() in eventHandler: if the event type is changed and race is not null, race, currentlyRunning, racerQueue, racerLanes, and trigMementos are set to null so that a new race matching the new event type will be created when the user enters a racer to the new race.
Merge branch 'JoannasRaceChanges' of https://github.com/hawkin29/ChronoTimer1009 into JoannasRaceChanges