Specify SLURM arguments

When submitting jobs on the ifi-gpu cluster, i often need to adapt some slurm properties of the generated job file. For example, i sometimes need to specify a partition of the cluster directly (e.g., IFItitan), or add a property like --exclusive.

We could either add an option which generates the slurm job, but not submit it, so that it can be edited, or think about a more complex list of options which would write the correct properties into the slurm job file.