migration of TrackDetectorAssociator
define dead regions
return back lazy initialisation at the first step to avoid crash
Merge pull request #3447 from dr4kan/migration_TT_AT_ver3

Consumes -- Migration of TrackDetectorAssociator
Merge pull request #3526 from civanch/g4_user_actions

Sim -- Define dead regions
Merge remote branch 'origin/CMSSW_7_1_X' into CMSSW_7_0_X