SimWatchers and SimProducers need to be in TLS too
Coalesce thread_locals in RunManagerMTWorker to a single thread_local struct
Move to std::shared_ptr from boost:: in SimG4Core
Merge pull request #4884 from makortel/geant10mt_cleanup

SimG4Core -- Coalesce thread_local statics in RunManagerMTWorker into one struct, and change boost::shared_ptr to std:: in SimG4Core