Making dEtaIn seed available for ID purposes

[Sam-Harper]

This pull request simplifies the calculation of the new ID variable dEtaInSeed presented recently in the e/gamma meeting. As the name suggests, it is dEtaIn but computed using the eta of the seed cluster rather than the supercluster. It is simply dEtaIn-sc eta + seed eta. I have added a function to GsfElectron which makes it, it would be nice if we could have this, it just simplifies things and avoids mistakes but we can live without.

I have also added a class to the ID framework which can cut on this variable.

[cmsbuild]

A new Pull Request was created by @Sam-Harper for CMSSW_7_3_X.

Making dEtaIn seed available for ID purposes

It involves the following packages:

DataFormats/EgammaCandidates
RecoEgamma/ElectronIdentification

@cmsbuild, @nclopezo, @StoyanStoynev, @slava77 can you please review it and eventually sign? Thanks.
@lgray this is something you requested to watch as well.
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@nclopezo, @ktf you are the release manager for this.
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[StoyanStoynev]

@cmsbuild please test

[cmsbuild]

+1
Tested at: 1da8e96
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-6300/766/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-6300/766/summary.html

[StoyanStoynev]

+1
Tested 1da8e96 on top of CMSSW_7_3_X_2014-11-09-1400 - short matrix tests. No diffs (despite false positives in jenkins). The code only adds optional function and a class (that is - not run by default).

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_3_X IBs unless changes (tests are also fine). This pull request will be automatically merged.