#17 add 'playOne' query parameter, which plays a challenge repeatedly with max quantities (for performance testing)
hide 'Test' button in Game if 'playAll' or 'playOne' query parameters are present, not intended for these situations
#17 When 'dev' query parameter is present, display time required to switch challenges at bottom center. Defer removal of previous ChallengeNode until animation frame after the new ChallengeNode is displayed.