Added Nimrod implementation.

Some things to note:

* To compile the code you will need the latest compiler from [git HEAD](https://github.com/Araq/Nimrod).
* The code depends on openmp.

I hope that's ok. I can get rid of the openmp dependency easily but the ``||`` operator is too cool and the speed is exactly the same anyway. Compiling the resulting C code with clang results in a slower application btw.

Let me know if there are any problems!