Overload `new` and `exit`

[fidian]

The test_helpers plugin provides useful functionality that I'd love to see here in runkit. Is there a way you can grab its code to overload the new operator and exit so I can switch my legacy code tests over entirely to runkit? Its license is MIT and the github project is at https://github.com/sebastianbergmann/php-test-helpers. It compiles against PHP 5.4 but the function renaming doesn't work well in the updated PHP version.