class RooAbsOptTestStatistic: public RooAbsTestStatistic

 Default implementation returns sum of components

 Driver function to propagate const optimization

 This method changes the value caching logic for all nodes that depends on any of the observables
 as defined by the given dataset. When evaluating a test statistic constructed from the RooAbsReal
 with a dataset the observables are guaranteed to change with every call, thus there is no point
 in tracking these changes which result in a net overhead. Thus for observable-dependent nodes,
 the evaluation mechanism is changed from being dependent on a 'valueDirty' flag to guaranteed evaluation.
 On the dataset side, the observables objects are modified to no longer send valueDirty messages
 to their client