fix array overflow issues found by David A.

Issues reported at
https://hypernews.cern.ch/HyperNews/CMS/get/swReleases/4108/1/1/1/1/1/1/1/1.html
and follow ups are mostly fixed here. 
I understand it is an "old" code optimized but:
eta is defined as "float eta = fabs(superCluster.eta())" which it shouldn't (I think) but 
as is  TMath::Abs is unnecessary and moreover in any of the places std:abs is a better choice; absEta is better to be float here.