getObservationNames - Return DataSet's Observation Names
 
    obsNames = getObservationNames(self) Return a cell array of
    an object's observation names; if setObservationNames has not been
    called or the 'observationNames' field was not set at construction,
    default behavior is to return sprintf('Observation %d',i) for all
    observations.
 
    obsNames = getObservationNames(self,indices) Return the observation
    names for only the specified indices.