Updated unit test for BigInteger patch (#4837946)

[Tim Buktu]

I updated BigIntegerTest so it tests the existing multiplication and
division algorithms as well as the ones added by my (and Alan's)
BigInteger patch.

This patch also adds a 6th type of random number to the 5 already
present. The new type outputs random numbers that contain long runs of
1-bits and 0-bits. GMP uses these numbers because apparently they are a
good way to trigger bugs in bigint arithmetic.

The patch is at https://gist.github.com/1586984
The whole BigIntegerTest.java file is at https://gist.github.com/1586990

I forgot to mention in my previous email that this is for bug 4837946.
Thanks,

Tim