collapse the scheduling table when possible to reduce the
number of time slots to check for pending jobs. This should
improve performance considerably.

Previous logic was sometimes building incomplete map

When a decision is made to start a job, if for some
reason that job's start failed, the backfill scheduler
would previously just exit. With this change, it logs
the event and reserves the resources expected to be
used and continues down the job queue.

This change prevents creation of some back-to-back records with
the same resources, but different times.

No change in logic

Improved logging of backfill scheduling actions
Better handling of backfill_resolution logic to avoid creating
   some records that are not needed
Avoid creating some backfill scheduling maps with zero duration
The net effect should be slightly improved performance with no
   significant difference in action

Update slurm.conf man page for DebugFlag BackfillMap. This should be
considered part of commit 3c2bffb6

Add DebugFlag of BackfillMap. Previously a DebugFlag value of Backfill
logged information about what it was doing plus a map of expected resouce
use in the future. Now that very verbose resource use map is only logged
with a DebugFlag value of BackfillMap

Log not only the count of jobs tested since the last time locks
were released, but also the total job count since the backfill
scheduler started.

Remove duplicate backfill scheduling tests. For example there is
no need to test if a job can be started if the only difference
from the previous test involves nodes in other partitions that
can not be used by the job we are trying to start.

The backfill scheduler was always reporting the time that a job
was being considered as NOW rather than the time that was really
being considered.

decreases and total is less than in use.

This is a correction to commit 308b7432

Improve how failures in slurmd/slurmstepd communications are logged.

mail messages for job array events print now use the job ID using the
format "#_# (#)" rather than just the internal job ID.

Cray network.

Cray/ALPS system - Enable backup controller to run outside of the Cray to
accept new job submissions and most other operations on the pending jobs.

* Handle a missing ALPS spool directory
* Update debug statements to work like the switch plugin
* Move some code into static functions
* Keep track of the number of active job steps and call
  alpsc_node_app_epilogue

Add child_forked() function to the slurm_acct_gather_profile plugin to
close open files, leaving application with no extra open file descriptors.