Changed the 'iceTime' to the more general 'event' in order to store all
of the events that occur for the skater (costume measurements, skate
sharpenings, ice time).  This will make it possible to track important
metrics like ice time since last sharpening and average ice time between
sharpenings.  And it will make it possible to keep track of the most
recent costume measurements and how 'stale' they are.