Rewrite/Refactor of PFBlockAlgo -- SLHC Edition

[lgray]

6_2_X_SLHC10 backport of #3385

Tested in SLHC10, technical migration with minor regressions from order-dependencies in PFAlgo.
Further information in 71X PR.

If necessary I can rebase to a more recent IB.

[cmsbuild]

A new Pull Request was created by @lgray (Lindsey Gray) for CMSSW_6_2_X_SLHC.

Rewrite/Refactor of PFBlockAlgo -- SLHC Edition

It involves the following packages:

DataFormats/ParticleFlowReco
HLTrigger/Configuration
RecoParticleFlow/PFClusterTools
RecoParticleFlow/PFProducer
RecoParticleFlow/PFRootEvent

@perrotta, @cmsbuild, @thspeer, @fwyzard, @Martin-Grunewald, @anton-a, @nclopezo, @slava77, @Degano can you please review it and eventually sign? Thanks.
@bachtis this is something you requested to watch as well.
You can sign-off by replying to this message having '+1' in the first line of your reply.
You can reject by replying to this message having '-1' in the first line of your reply.
@andersonjacob, @mark-grimes you are the release manager for this.
You can merge this pull request by typing 'merge' in the first line of your comment.

[mark-grimes]

Tests 10000, 10200, 10400, 11200, 11400, 12000, 12800, 13000, 13600 and 14600 pass all steps.
Tests 12200, 12400, 12600, 13800, 14000, 14200 and 14400 fail in step 2 with known errors.
Pretty sure none of these check the change though.
On the latest IB only changes 78 files - the RecoParticleFlow/PFRootEvent package was taken out by #3347. Other than that the only file common between the pull requests appears to be DataFormats/ParticleFlowReco/src/classes_def_2.xml and there are no conflicts.
Don't quite understand the implications of the "will require additional commits later" comment on #3385, will wait for a discussion in the ORP tomorrow before merging.

[lgray]

The "will require additional commits later" refers to the HLT updates from Martin Grunewald, they're not pertinent for SLHC.

[lgray]

Do you need me to rebase? for the PFRootEvent issue, or does that merge well?

[mark-grimes]

merge

"they're not pertinent for SLHC" - fair enough, merging.
"Do you need me to rebase?" - no, it merges okay. It was more a comment to draw attention to the important points when viewing "Files changed".