Renames some sview variables for better clarity and put some node
  fields into alphabetic order

This commit adds support for free_mem as part of the sinfo
command using the key 'e' ('f' and 'F' are already taken).

This commit adds information about the free memory to the
output created by slurm_sprint_node_table(). The unit of
FreeMem is MiB like RealMemory.

This commit adds a new field free_mem to the node_info struct
and augments the 15.08 RPC protocol to exchange this information
as part of the ping and registration status messages. The
free memory is taken from the sysinfo() information on systems
that support this function. Overall, the implementation sticks
to the way cpu_load (the 5 min load average) is handled.

2 now arrays of limits

Conflicts:
	src/slurmctld/acct_policy.c

note the change and remove the new time limit if the job is requeued.

and give different error codes for different limits violated.

A job being considered for backfill scheduling can have its time
  limit altered to the partition limit, job minimum time limit,
  etc. This fixes two places where the backfill scheduler could
  leave the job in a pending state with a time limit different
  from it's original value.

add more startup/initialization logic
fix some locking issues
fix some issues related to persistent buffers

after this check in nor will sacctmgr

argument "size" to _print_topo_record() could be zero, resulting in
  invalid array size specification of zero.
Dead assignment to "len" in second call to _print_topo_record().