Replace CLHEP matrices by root::SMatrix in segment fitter

[ptcox]

This is the straight swap of CLHEP matrices by root::SMatrix in the least-squares fitting of CSC segments. Really the code needs a lot of factoring and general clean-up but I don't have the time - a good place to start would be to factor out the segment-fitting. (That would probably also help GEM since I think they also make use of the same code, by cut-and-paste from CSC.) I also fixed what I consider a bug where after manipulations apparently to improve the numerical robustness of covariance matrix handling, the symmetricity of the covariance matrix was not maintained. This leads to ~8% of segments receiving slightly difference local positions and directions.I decided not to change the ME1/1A max rechits in cluster from 24 to 20, as in the other chambers, even though in postls1 the channels are now unganged - it seems that would be more effort than it's worth (would required setting up separate pre- & post-ls1 configs, AND changing HLT configs to match.) Finally, I noticed there is something called a 'yweightPenaltyThreshold' that was not set for ME4/2. I used the same value as set for ME/2 and ME3/2. I made a lot of tests comparing the original code, the new code, the new code with general rather than explicitly symmetric SMatrix, and the old code with the bug-fix enforcing symmetric covariance matrices. Everything seems consistent. First results of modified code presented in CSC Meeting of 20-Aug-2014, https://indico.cern.ch/event/336061/. Since then I have also increased the study samples to 1000 events of run 1 SingleMu, giving 4500 segments, and everything still makes sense. The runTheMatrix reco test ran fine.

[cmsbuild]

A new Pull Request was created by @ptcox for CMSSW_7_2_X.

Replace CLHEP matrices by root::SMatrix in segment fitter

It involves the following packages:

RecoLocalMuon/CSCSegment

@cmsbuild, @nclopezo, @StoyanStoynev, @slava77 can you please review it and eventually sign? Thanks.
@bellan this is something you requested to watch as well.
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[cmsbuild]

+1
Tested at: 2061bbf
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-5125/764/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-5125/764/summary.html

[StoyanStoynev]

Tested 2061bbf on top of CMSSW_7_2_X_2014-09-05-1400.
The observed differences are expected due to the bug fix. CSC segments are affected a bit (here I am showing wf 22, 1 TeV muons; lower pt muons or non-muon wf are affected much less):

The affect the STA and global fits:


and also MET:

Again, in other wf ( ttbar events), changes - in particular MET - are invisible.

[StoyanStoynev]

+1
Based on the review above, no issues with the code itself.
The PR gets rid of CLHEP matrices in the local CSC code and fixes a long lived bug. Changes affect mostly higher pt muons, PF objects are overall hardly affected, especially in typical running. In any case analyses should benefit from the bug fix.

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_2_X IBs unless changes (tests are also fine).