array elements.

job string format.

was using array_job_id rather than job_id for non-array job

Do not return ESLURM_ALREADY_DONE on cancel of a job array unless
the entire array is done

the jobid string. Reuse the existing job_step_kill_msg_t structure.

if no other command line options are specified.

This is the infrastructure needed to modify a job array with the
new job array data structures. There will need to be additional
work once the RPC is fleshed out.

Previously would not work properly if a job array to be canceled was partly running and partly pending

This is important for job array modifications. Log the job ID in the job record rather than in the modify request.

For improved support of job arrays

which then kill the job or the job array.

Added SchedulerParameters options of bf_max_job_array_resv to control how
many tasks of a job array should have resources reserved for them.

Modify to work if the bitmap sizes of the job and user specification vary.

This adds a new function job_str_signal() which can be used to
cancel/signal a job array using a single RPC rather than a series
if RPCs, one per job record, which does not work with the new
job array data structure. This new logic is untested.