allow jagged arrays in implicit cast

[dotChris90]

• related to Jagged arrays are not allowed here! #186
• now they are allowed check unit test

            double[][] a = new double[3][];
            for(int idx = 0; idx < a.Length;idx++)
                a[idx] = new double[2];

            
            for (int idx = 0; idx < 3;idx++)
                for (int jdx = 0; jdx < 2;jdx++)
                    a[idx][jdx] = 10 * idx + jdx;

            NDArray b = a;