Clean up likelihood algorithm (parts of code now executed before creation of database object) + updated DBWriter

[tomcornelis]

This pull request includes:

• Introducing a weight for each likelihood variable, which will be used to get a better performance for high pt jets (see JMAR meeting 11 December 2014)
• Small optimization of the algorithm when dealing with empty bins in the tails of the pdf's
• Some clean-up and optimizations on the QGLikelihoodDBWriter code (the input src files and created QGL_v1.db file can be found at /afs/cern.ch/user/t/tomc/public/qgTagger/QGLikelihoodDBFiles)

[cmsbuild]

A new Pull Request was created by @UAEDF-tomc (Tom Cornelis) for CMSSW_7_4_X.

Including weights in the likelihood algorithm + updated DBWriter

It involves the following packages:

CondFormats/JetMETObjects
JetMETCorrections/Modules
RecoJets/JetAlgorithms

@apfeiffer1, @nclopezo, @monttj, @cmsbuild, @StoyanStoynev, @slava77, @ggovi, @vadler can you please review it and eventually sign? Thanks.
@rappoccio, @ahinzmann, @mmarionncern, @nhanvtran, @schoef, @mariadalfonso, @TaiSakuma this is something you requested to watch as well.
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[slava77]

why can't the histogram already be pre-filled by (Qi/Qw)**weight values. It seems like it's uniquely defined by var_i -> binIndex?

[tomcornelis]

Hmm yes, probably it is possible to move most of this stuff to filling the histogram, I'll look into this

[cmsbuild]

Pull request #7057 was updated. @apfeiffer1, @nclopezo, @cvuosalo, @monttj, @cmsbuild, @slava77, @ggovi, @vadler can you please check and sign again.

[tomcornelis]

As requested by @slava77 I prefilled the histograms with (Qi/Qw)**weight (including the parts of the code where I take care of empty bins, also helps to get rid of these hard-coded values we had there).

[cmsbuild]

Pull request #7057 was updated. @apfeiffer1, @nclopezo, @cvuosalo, @monttj, @cmsbuild, @slava77, @ggovi, @vadler can you please check and sign again.

[slava77]

please test

[cmsbuild]

The tests are being triggered in jenkins.

[tomcornelis]

@monttj I guess you have to sign again after this small update

[monttj]

+1

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_4_X IBs unless changes (tests are also fine). This pull request will be automatically merged.