Adding the evaluation framework

Mostly written by Christoph Deleuze. I just use it to compare my system
to his: as expected it is slower. Finer points:
- The overhead seems to be proportional to the number of threads (no
suprise there, scheduling is inherently unfair at the moment)
- But it starts off as 10x slower and gets worse.
- Overall, if you are looking for speed, this is not good....