Add seff support to evaluate resource allocation after executation

[sreichl]

Employ slurm command seff for each finished job and append output to the respective slurm-job log file to get statistics on resource usage. Over time this can help to raise awareness of more appropriate resource allocation.

[cmeesters]

Interesting idea. It's not going to happen 1:1 because seff is just a Perl wrapper around sacct. ;-)

However, we query sacct anyway. To extend this call and report resource usage is certainly feasible. What I would not like is to see the Memory efficiency reported by seff: this is nonsense because for some application we have to reserve a full node and hardly use memory. Yet, seff will calculate the ratio between the memory of a fully reserved node and a low memory footprint. Bad idea. I would just enjoy reading the delta.

Note: I am willing to code that, will not do it because of obligations until mid-October. If you submit a PR sooner, it will be considered.

[sreichl]

Cool, I am happy to wait. It would be nice to have, not a must-have-now. Thanks for your considerations and the executor plugin!

[cmeesters]

@sreichl has been accomplished with PR #221 and is in v1.5.0, see #328