Fix handling of weights in generator interfaces (53x backport)

[bendavid]

Fix handling of weights in generator interfaces

[cmsbuild]

A new Pull Request was created by @bendavid (Josh Bendavid) for CMSSW_5_3_X.

Fix handling of weights in generator interfaces (53x backport)

It involves the following packages:

GeneratorInterface/Core
GeneratorInterface/Pythia8Interface
SimDataFormats/GeneratorProducts

@vciulli, @covarell, @thuer, @cmsbuild, @nclopezo, @bendavid can you please review it and eventually sign? Thanks.
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[cmsbuild]

+1
Tested at: 2f457f0
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-7361/2109/summary.html

[bendavid]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_5_3_X IBs unless changes (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @smuzaffar, @ktf

[davidlange6]

+1