Permit the feature structure for nodes to be completely cleared (set to NULL not pointer to empty string).

will re-read any configuration files. Desired for wiki and 
wiki2. Likely required for gang.

    patch.1.2.0-pre10.061214.affinity_stepid from Dan Palermo (HP).

  could result in reading data too often.

Add jobacct_g_resume_poll() so thing don't fall hopelessly out 
  of sync if a message gets lost or replayed.
Restore logic to close /proc directory on shutdown (removed 
  by Danny is recent update causing file leak).