53X back-port of Pdf Weight modifications

[fabiocos]

Back-port into 53X of the Pdf Weight code modifications introduced in order to allow to use one of the computed PDF sets as denominator for weight definition. Set also a protection to force PDF information to be written according to the LHAPDF parton code (i.e. gluon code must be 0 and not 21 as it is in sherpa).

[cmsbuild]

A new Pull Request was created by @fabiocos (Fabio Cossutti) for CMSSW_5_3_X.

53X back-port of Pdf Weight modifications

It involves the following packages:

ElectroWeakAnalysis/Utilities

@cmsbuild, @vadler, @Degano, @nclopezo can you please review it and eventually sign? Thanks.
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@smuzaffar you are the release manager for this.
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[vadler]

+1
Hmm, I though, I have signed this already before the weekend...
Could the (commented) debugging output still be removed?

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_5_3_X IBs unless changes or unless it breaks tests. @smuzaffar can you please take care of it?

[davidlange6]

+1

[smuzaffar]

+tested