2-1 error with no color in pawn class
so add white
2-2 make string color in pawn class
2-3 Board class add
2-4, 2-5 add method in board and add javadoc
2-6 add chess package
2-7 move pawns to pieces package and add public
2-8 make error
2-9 don't know test sweet...
2-10 pawn delete unneed codes