[constant-trickery] Turn existing BigIntegerTest into an abstract TestCase.
[constant-trickery] Add PhpseclibTestCase. No longer use PHPUnit directly.
[constant-trickery] Provide infrastructure for setting mode constants.
[constant-trickery] Add extra test cases for BCMath and GMP.
[constant-trickery] Add runkit to PHP. Thanks to kherge for those lines.
[constant-trickery] Try to use runkit to redefine mode constants.
[constant-trickery] Also skip tests when required extension is missing.
[constant-trickery] Reimport class definition to clear static variables.
Merge pull request #48 from bantu/constant-trickery

Run BigInteger tests for all implementations if possible.
Merge remote-tracking branch 'upstream/master'