Sfm parallel

I added the parallelization setup from the GNM in the SFM for speedup. I tested the results in a small scenario (fixedSeed) once and they were identical - with a speedup in computation time.

It would be great if one of you could have a look at it and approve it if you believe that it makes sense - just to make sure that I'm not messing sth up (it's 34°C ;))

Thanks!