lesson 1:
    - static initializer used in Mines.java
    - static initializer used in MinesUI.java
    - method overloading in Mines.java > startNewGame()

lesson 2:
    - inheritance in Mines.java (extends GameBoard)
    - custom exception in InvalidMoveException.java
    - throwing exception in Mines.java > reveal()
    - catching exception in MinesUI.java > handleReveal()

lesson 3:
    - method overriding in Mines.java > reset()
    - substitution via GameBoard parent reference in constructor chain

lesson 4:
    - abstract class in GameBoard.java
    - abstract method reset() in GameBoard.java
    - implementation of abstract method in Mines.java > reset()

lesson 5:
    - collections in MinesUI.java > List<Button> buttons
    - iterators in MinesUI.java > disableAllButtons()

lesson 6:
    - lambda expressions in Mines.java > forEachNeighbor()
    - lambda expressions in MinesUI.java > button.setOnMouseClicked()

lesson 8:
    - Scanner used in Mines.java > loadBestScore()
    - BufferedReader used in Mines.java > loadBestScore()
    - BufferedWriter used in Mines.java > saveScore()
    - File used in Mines.java > loadBestScore()

lesson 9:
    - JavaFX GUI in MinesUI.java
    - JavaFX application entry class in MyGame.java > start()

lesson 10:
    - unit tests to be shown in accompanying JUnit test files