step launch struct.

in index lists AND in ranges.  Here is how negative numbers work in
ranges:

 If both numbers in a range are of the same sign (both positive, or both
 negative), then the range counts directly from the first number to the
 second number; it will not wrap around the "end" of the node list.

 If the numbers in a range differ in sign, the range wraps around the
 end of the list of nodes.

 Examples: Given a node allocation of foo[1-16]:

	-2-3  (negative 2 to positive 3) becomes foo[15-16,1-4]
	3--2  (positive 3 to negative 2) becomes foo[4,3,2,1,16,15]
	-3--2 becomes foo[14-15]
	-2--3 becomes foo[15,14]
	2-3   becomes foo[3-4]
	3-2   becomes foo[4,3]

only relevant to job allocations.

Add -T/--task-layout-byid which allows task layout by relative nodeid with the
  allocation.  For instance, given nodes foo[1-16] in an allocation, the command
  slaunch -T 1,[3-4],1,3,8,-1,0,-1 will run on tasks on nodes in the following
  order: foo[2,4-5,2,4,9,16,1,16]
  Notice that negative numbers are permitted.

Task layout by nodename is now -Y/--task-layout-byname.

The --relative option now allows a negative number.  -1 is the last node in
the allocation.

slaunch will now cancel a job step on SIGINT, SIGHUP, and SIGTERM.  If
a signal it caught, it will signal the step to terminate and wait up
to 10 seconds for all remote nodes to report that the tasks have exited.

After 10 seconds, it will give up waiting and exit, regardless of the
state of the job step.

step_launch api code.

It now allows a comment on the line, quotes to group characters together
(to allow whitespace in arguments), and a backslash escape character
to allow inclusion of #, \, ", etc.

slaunch) from src/api/step_pmi.[ch] to src/api/pmi_server.[ch].

Also, delete srun's personal copy of the pmi server code and have it
build against the copy in the shared src/api location.

Overhaul the command line parsing code to handle #SBATCH arguments in
  batch scripts.

Remove unnecessary multi-prog option (multi-prog is slaunch-only).

code from test18.14.

with and associated launcher.  A batch script only has job allocation-specific
variables set.

Add new SLURM_JOB_* environment variables.

variables are missing.