Proper usage of smart pointers

1. Remove the implicit ownership transfer

   • Sim/Scan/BeamScan

   BeamScan::BeamScan(Scale* axis): m_axis(axis)

   • Sim/Scan/PhysicalScan -> BeamScan

2. Remove unneeded usage of std::shared_ptr

   • Sim/Simulation/ScatteringSimulation.h: L72:

   std::shared_ptr<Beam> m_beam;

   • Device/Beam/Beam.h: L100:

   std::shared_ptr<IFootprint> m_footprint;

   • Device/Detector/OffspecDetector.h: L77:

   std::shared_ptr<Scale> m_axes[2];

3. Check CloneableVector usage.