Further cleanup of tr_gss and usage for tids handling

Further cleanup of tr_gss and usage for tids handling

The trust router now builds, but the monitoring parser tests do not.

  * Eliminate extra layer of auth callback when using tr_gss.c, services
    using it now need only one auth callback
  * Document tr_gss.c's intended usage
  * Flesh out the MONS_INSTANCE structure
  * Fix a couple more pedantic data typing errors