Add support for job array options in the qsub command, in #PBS
options for sbatch scripts and set the appropriate environment
variables in the spank_pbs plugin (PBS_ARRAY_ID and PBS_ARRAY_INDEX).
Note that Torque uses the "-t" option and PBS Pro uses the "-J"
option.

slurm.conf.  Rebooting daemons after adding nodes to the slurm.conf
is highly recommended.

Rather than continuously retrying a step create for suspended jobs,
add a sleep with exponential backoff

If a job is suspended, log the step create failure using debug
rather than info in slurmctld

The test for NRT_NULL_MAGIC failed to capture some problems
if the pointer to the structure was NULL. This is an ammendment
to commit 2a55aa0b

Perhaps should also look into doing this for nodeinfo and libstate

this would cause pmd's to hang.

code.

interval.

merged together.

sacct.

Add support for SchedulerParameters value of bf_max_job_start that limits
the total number of jobs that can be started in a single iteration of the
backfill scheduler.
bug 607

A test for bf_max_job_user was > rather than >=

Since the QOS priority is 32-bits, base the preemption priority
upon that 32-bit field and ignore the job size.
Variant of commit  a3e74ef2