add Geant namespace

src/HEP/Geant/Scene.cpp

@@ -44,6 +44,7 @@
 #include "ActionInitialization.hh"
 
 namespace uLib {
+namespace Geant {
 
 class SceneDetectorConstruction : public DetectorConstruction {
 public:
@@ -146,4 +147,5 @@ void Scene::Initialize() {
   d->Initialize();
 }
 
+} // namespace Geant
 } // namespace uLib