Move slurm_step_layout_t struct to slurm.h.in so we can use it as the
returned object of a future API function.

altered the resource allocation and job_step_create_response structures.  Also altered the step_layout structure

Make NO_VAL for relative mean don't-use-relative offset.

--task-layout and --task-layout-file options.

Also have the slurmstepd set the SLURMD_NODENAME env variable.

something...

Remove debugging message.

requested.  For instance "slaunch -w foo[4,2,2,2,2,4,4] -n3" will only
launch 3 tasks on foo[4,2,2], and only asks the controller for foo[4,2,2].
If it asked for the whole string, scontroller would balk.

there are entries in the nodelist

Now if a line BEGINS with "Include" and is followed by whitespace and then
a filename, the parser will open and parse that file before continuing to
parse the rest of the current file.

Also improved some parser error messages with line numbers and file names.

Now, there may only be ONE key-value pair per line, EXCEPT on lines
that BEGIN with key-value pairs such as NodeName and PartitionName, which
explicitly accept additional values.

This allows us to eliminate redundant listing of ignored keys...