added uebung04 task

uebung04/chess/Chess.java

@@ -0,0 +1,15 @@
+package chess;
+
+public class Chess {
+  public static void main(String[] args) {
+    final Board board = new Board();
+    final Piece p1 = new Queen(Color.black, board, 1, 4);
+    final Piece p2 = new Queen(Color.white, board, 8, 4);
+    final Piece p3 = new Knight(Color.white, board, 3, 3);
+    final Piece p4 = new Knight(Color.black, board, 6, 4);
+    System.out.println(board);
+    System.out.println(board.toString());
+    board.printBoard();
+    board.check();
+  }
+}