Benchmark: Whetstones

[StephenG1CMZ]

I have attempted an implementation of the original Whetstone benchmark algorithm in PPL.

This was primarily a learning exercise to remind myself what the benchmark consisted of and to discover whether it was implementable in PPL.

Disclaimer: The implementation is unverified both in accuracy and timings.

If comparing accuracy of results with on-line sources, remember that there are several Whetstone benchmarks, so you might not be making a valid comparison.