- modify readUserInput() method to make sure user input is only l, r, u, d, or q "ignoring case"
- add data 2 dimentions array of integers to store game data.
- modify displayBoard() method to display values of data 2 dimensional array.
- add tiltLeft() , tiltRight(), tiltUp() , and tiltDown() method signatures.
- call proper method "tiltLeft(), tiltRigh()t, tiltUp(), or tiltDown()" based on user input "L, R, U, D".
- implement tiltLeft() method, to tilt borad data to the left direction
- add testTiltLeft() method to test logic of tiltLeft() method
- implement tiltRight() method, to tilt borad in the right direction
- add testTiltRight() method to test tiltRight() method logic.
- add and implement getRandomNumber() method to generate random number between 0 and 3 inclusive
- add and implement populateRandomCell() method to populate an empty random cell with random value of 2 or 4
- fix generaterandomNumber() method
- implement tiltUp() method, to tilt board in up direction.
- add testTiltUp() method to test tiltUp() method logic.
- aimplement tiltDown() method to tilt board in down direction.
- add testTiltDown() method to test tiltDown() method logic