Do cmake_minimum_required centrally in one single place

CMakeLists.txt

FSL/CMakeLists.txt

FullSimLight/CMakeLists.txt

FullSimLight/Plugins/CMakeLists.txt

...orPlugins/FSLExamplePrimaryGeneratorPlugin/CMakeLists.txt

...ticFieldPlugins/UniformMagneticFieldPlugin/CMakeLists.txt

.../PhysicsListPlugins/FSLTestPhysListPlugins/CMakeLists.txt

...Examples/SensitiveDetectorPlugins/SDPlugin/CMakeLists.txt

...imLight/Plugins/Examples/UserActionPlugins/CMakeLists.txt

...es/UserActionPlugins/DummyUserActionPlugin/CMakeLists.txt

...mmyUserActionPlugin/DummyUserActionsPlugin/CMakeLists.txt

FullSimLight/Plugins/HitsPlugin/CMakeLists.txt

FullSimLight/Plugins/TracksPlugin/CMakeLists.txt

FullSimLight/perf/CMakeLists.txt

GeoModelCore/CMakeLists.txt

GeoModelExamples/CMakeLists.txt

GeoModelExamples/GeoActions/CMakeLists.txt

GeoModelExamples/GeoActionsCountNodes/CMakeLists.txt

GeoModelExamples/GeoFullPhysVol/CMakeLists.txt

GeoModelExamples/GeoShapeExamples/CMakeLists.txt