Make history registry non-singleton and also fix read calls to not use pointers
Merge pull request #681 from wmtan/TwoFrameworkImprovementsForMultithreading

Make history registry non-singleton and also fix read calls to not use p...
Merge branch 'CMSSW_7_0_X' containing pull request #681 into multipleStreamsInEventProcessor

Resolved minor overlapping change in EventProcessor.cc and SubProcess.cc. In both cases the
resolution was to use the change already in this branch.