new caching of MagneticField in GlobalTracjetoryParameters - from M.Tadel
protection against null MF
Histogram booking moved to beginRun
Move verbose printout and add parameter safety
Make all registry data members non-mutable
Merge pull request #55 from cerati/cerati/cacheMFinGTP

New caching of Magnetic Field in GlobalTrajectoryParamters class
Merge pull request #149 from mkirsano/mydevjuly2

Move verbose printout and add parameter safety
fixed conflict in the name of the author
Merge pull request #167 from wmtan/AllRegistryDataMembersNonMutable

Make all registry data members non-mutable
Merge pull request #169 from deguio/Histogram_booking_moved_to_beginRun

Histogram booking moved to begin run  (was #60)