Incorrect values for the "or" function

[HoangNguyen219]

Describe the bug
Incorrect values for the "or" function

Issue 1: Incorrect values
To Reproduce

    @Test
    fun testOr() {
        val a = BigInteger.parseString("-1")
            .or(BigInteger.parseString("11"))

        assertEquals(
            BigInteger.parseString("-1"),
            a
        )
    }

Expected :-1
Actual   :-11

Expected behavior
In java.math this test is successful:

    @Test
    public void testOr() {
        BigInteger a = new BigInteger("-1")
                .or(new BigInteger("11"));
        assertEquals(new BigInteger("-1"), a);
    }

Issue 2: When perform or function between a Number and Zero throw an exception
To Reproduce

    @Test
    fun testOr() {
        val a = BigInteger.parseString("0")
            .or(BigInteger.parseString("11"))

        assertEquals(
            BigInteger.parseString("11"),
            a
        )
    }

sign should be Sign.ZERO iff magnitude has a value of 0
java.lang.IllegalArgumentException: sign should be Sign.ZERO iff magnitude has a value of 0

Expected behavior
In java.math this test is successful:

    @Test
    public void testOr() {
        BigInteger a = new BigInteger("0")
                .or(new BigInteger("11"));
        assertEquals(new BigInteger("11"), a);
    }

[ionspin]

Thanks for reporting, I'll give it a look when I have some free time.

[ionspin]

I think that first part of the issue presumes that -11 is represented in two's complement, which is not the case in this library. I'd have to investigate a bit more before deciding on the solution.