In this assignment, I want you to get experience with Tab Bar and Navigation controllers, Table Views, and storing information in UserDefaults. The app won't do anything especially interesting but it gives practice that should be useful.

At the top level your app should have three tabs.

1. The first tab should present a table view that lists known users/players/registered people (initially the list can be empty). There should be a way to add a new person to the list. Touching/selecting a table view item should present (via a navigation controller) a more detailed screen with some information about the selected person. On this more detailed screen, there should be (in addition to the person's name):
   • a button, or other widget, that, if touched, sets the person as "active user" of the overall app (no passwords or other things are required. It simply sets some notion of "active user" to this particular person.)
   • the last value on the calculator's display (tab 2) when this person most recently used the calculator (even if app was completely closed/terminated after the most recent use - this is where UserDefaults can be used)
   • the highest score this person has ever achieved on the tapping game (tab 3)
   • the date and time when this person last became the active user
2. The second tab should present a calculator (either your own version or the basic one I originally developed in class)
3. The third tab should present a very simple game. It should contain a button that, when pressed, starts a timer (see Timer class and its scheduledTimer(timeInterval:invocation:repeats:) method) that lasts 10 seconds. During that 10 seconds, the number of taps on the screen should be counted. When the 10 seconds are finished, the total number of taps during the 10 seconds should be displayed as the game score.