Major update to src/common/node_select.h to document the API calls.
Minor updates to node select plugin web page.

The information describing the select plugin APIs did not reflect
modifications made in SLURM version 2.3. Documentation for many
functions was added and other function descriptions were modified.

Add flag to the select APIs for job suspend/resume indicating if the action
is for gang scheduling or an explicit job suspend/resume by the user. Only
an explicit job suspend/resume will reset the job's priority and make
resources exclusively held by the job available to other jobs. This change
is also needed for Cray systems with ALPS.

extern bool select_p_job_expand_allow(void);
Now only true for select/linear

These functions are crrently stubs.

Infrastructure in place plus logic in select/linear.

reording functions. Based upon work by Gerrit plus bug
fixes and documentation that I've added.

    gang scheduling module. Make identification of preemptable jobs an argument
    to the select_g_job_test function rather than calling preempt plugin from
    the select plugin. Make output of srun --test-only option include a list
    of preempted job IDs. 
    svn merge -r18780:18815 https://eris.llnl.gov/svn/slurm/branches/preempt.job.list

Updates some sun constellation documentation

svn merge -r 16016:16041 https://eris.llnl.gov/svn/slurm/branches/sun_snl

    (cons_res_preempt.patch from Chris Holmes, HP).

  and Moe Jette. There are still a couple of end-cases that need to be fixed. We also
  need to push the core identification out to the slurmd for task binding. sched/gang
  needs revision to support this too.

    that can impact node scheduling.