BigInteger:  small optimization to bitwise_not
BigInteger: fix previous fix
Merge pull request #448 from terrafrost/bits-change

BigInteger:  small optimization to bitwise_not

* terrafrost/bits-change:
  BigInteger: fix previous fix
  BigInteger:  small optimization to bitwise_not
Merge branch 'master' into php5

* master:
  BigInteger: fix previous fix
  BigInteger:  small optimization to bitwise_not