Modified the grid class

* added new member variables (and their getter/setter functions):
· _moveCount keeps a count of the moves that have been made
· _firstPlayer keeps track of which player was selected to go first

* modifed the isFilled() function to utilize the new _moveCount member
variable
Modified theForce.js

* copied some of the whoGoesFirst() function's logic into a new
function--initializeBoard()
* altered the whoGoesFirst() function to call the new initializeBoard()
function after setting the first player
* altered the boardReset() function to call the new initializeBoard()
function after clearing the board; also added a statement that will hide
the "main menu" if "Reset" is clicked from the "Main Menu" view
* altered the aiMove() function to set turnColor to blue; without this,
when the board is reset and the AI is the first player, the turnColor
(or background color) remains red after the AI has made the first move
Modified the Main Menu

* replaced the Restart.onClicked even to call theForce.boardReset()
* theForce.BoardReset()  handles hiding the menu