Let user retrieve the script that Xenon submitted

[sverhoeven]

Xenon constructs a job script for submission to the batch scheduler like slurm.

A user might want to fine tune this script, but at the moment the script can not be requested from Xenon.

Add ability to retrieve the job script.

[jmaassen]

Will add in 2.1

[jspaaks]

for the record, the generated script is printed as part of the log4j output if you increase the verbosity enough

[jmaassen]

Need a bit more of a use case for this one. May be useful in combination with a submitBatchJob(String) where a user defined script is provided directly (as discussed in #556).

Won't fix for now. May revisit in future.