Deckstar/React-tictactoe-tutorial-with-and-without-hooks-and-functional-components

The "old way" of doings things in React was to use class-based components. The React tutorial page (https://reactjs.org/tutorial/tutorial.html) has these as the main focus. However, the "New way" (i.e. hooks and functional components) is becoming more and more popular. I reworked the tutorial into purely functional components with hooks, as a little exercise.