Adding optional PU weighted neutral isolation to tau ID

Adding an option to run weighted neutral isolation for the tau isolation. The very same algorithm has been already implemented by #4131 for general use. As the tau isolation is calculated separately, it was necessary to implement this also within tau ID software.

The default RECO sequence is not affected, no changes expected.

The new option can be utilized via
```
--customise RecoTauTag/Configuration/addWeightedIsolation_cfi.addWeightedIsolation
```

The studies that show that this way of calculating isolation is superior to the previous ways of handling neutral isolation has been presented by Yuta at CPF: https://indico.cern.ch/event/322762/

I don't understand how - the filter is filtering PFCandidatePtr and 
filter2 is filtering PFCandidate. The isoNeutral and isoNeutral_weighted 
collections are composed from different objects, so it is not possible 
to assign one to the other... and I think it is vaste of time to convert 
PFCandidatePtr collection to PFCandidate collection, no? Or should I 
place explicit typecast everywhere?


On 11/09/14 15:23, StoyanStoynev wrote:
>
> In RecoTauTag/RecoTau/plugins/PFRecoTauDiscriminationByIsolation.cc:
>
> >        if ( filter(isoObject) ) isoCharged_filter.push_back(isoObject);
> >      }
> > -    BOOST_FOREACH( const PFCandidatePtr& isoObject, isoNeutral_ ) {
> > -      if ( filter(isoObject) ) isoNeutral_filter.push_back(isoObject);
> > +    if(!calculateWeights_){
> > +      for( auto const & isoObject : isoNeutral_ ) {
> > +	if ( filter(isoObject) ) isoNeutral_filter.push_back(isoObject);
> > +      }
> > +      isoNeutral_ = isoNeutral_filter;
> > +    }else{
> > +      for( auto const & isoObject : isoNeutralWeight_){
> > +	if ( filter2(isoObject) ) isoNeutralWeight_filter.push_back(isoObject);
>
> Maybe change the others to filter2 too then (should clearly be better, 
> no?)?
>
> —
> Reply to this email directly or view it on GitHub 
> <https://github.com/cms-sw/cmssw/pull/5255/files#r17419820>.
>

-- 
Dr. Pavel JEZ
postdoctoral researcher
Centre for Cosmology, Particle Physics and Phenomenology-CP3
Université Catholique de Louvain