ENH: ensemble results for sampleSets (#2388)

- in v2112 the functionObject results were only delivering values from
  the last set listed (ie, overwritten).

  Now that the values are properly scoped by the name of the set itself
  Eg, `average(lines,p)` for the average for 'lines' set, existing
  workflows will break.

  It thus makes reasonble sense to also handle results without a
  qualifier as ensemble values.

      average(p)    // Ensemble average of all listed sets