Thread pinning

Created by: dominikkiese

Instead of using numactl, we could also start using the JULIA_EXCLUSIVE environment variable. We lose the ability to assign threads to specific processors like Thread 1 to run on core 7 and Thread 2 to run on core 3, but that is not what we intended anyways. We just wanted to have a fixed assingment of threads to cores to avoid unnecessary cache flushes. export JULIA_EXCLUSIVE = 1 will pin N threads to the first N cores, which should be fine. With this we can also clean up the SLURM interface and remove the pinning flag.