Add PSR4 namespace to composer.json.
Use __construct.
Add namespace statement. Rename class.
Remove any include statement.
Use namespace in example code.
Reference to instances as BigInteger instead of Math_BigInteger.
Replace new Math_BigInteger with new static.
Adjust test cases using Math_BigInteger.
Some more documentation polishing in Math/BigInteger.php.
Update users of Math_BigInteger.
Correct the remaining case by using instanceof.
Merge pull request #361 from bantu/namespacify-biginteger

Namespacify BigInteger

* bantu/namespacify-biginteger:
  Correct the remaining case by using instanceof.
  Update users of Math_BigInteger.
  Some more documentation polishing in Math/BigInteger.php.
  Adjust test cases using Math_BigInteger.
  Replace new Math_BigInteger with new static.
  Reference to instances as BigInteger instead of Math_BigInteger.
  Use namespace in example code.
  Remove any include statement.
  Add namespace statement. Rename class.
  Use __construct.
  Add PSR4 namespace to composer.json.