Milestone 3

Completed Milestone 3
Rename file's name
deleted old file
Class Piece Refactory - by Adigun Jide Idris

Class Non_Visual_Piece and VisualPiece have a lot of attributes and
Functionallity in Common, so I created a super class called class
Piece.java that both subclass (VisualPiece and Non_Visual_Piece) shares
it attributes and functionality, Thus, reducing duplicated codes.
Rename Class

Rename class Non_Visual_Piece, Start_Game, and Chess_Data to
NonVisualPiece, StartGame and ChessData respectively to maintain class
name consistency
TypeChecking

a. Creat  a new class named “CurrentBoard.java”
b. Creat a new class named ”NormalBoard.java”,
c. Creat a new class named ”FlippedBoard.java”
d. Modify the class “board.java”