Fix typos in DDG4 manual, correct the Sigma entry for VertexSmear, add Mask, change Mask type to int.bitmask everywhere

DDG4.py Output2ROOT: Only add '.root' extension if it is not already present. Consistent with lcio output

DDG4Doc: Add note about direction to vertexBoost, remove duplicate section about VertexBoost, rename third VertexBoost to VertexSmear and change class/file name accordingly

   subclasses 

   and DD4hep_CaloFaceBarrelSurfacePlugin:
     - create sensitve layers at the face of 
       a polyhedral calorimeter
     - to be used for track state AtCalo

    - re-included implementations for CylinderSurface
      methods (u,v,nornaml,...)
    - use multi_map in SurfaceManager 
      -> transparent to code expecting map
      lookup but provideds all surfaces when
      iterating
    - fixed Surface::distance using localPoint

      a polymorphic pointer of type VolSurfaceBase
      - this should facilitate the creation
        of dedicated surface classes for special cases
        such as inside the beampipe or the face of the calorimeter

Fixed Coil Rmin/Rmax swap bug in ILD/CLIC convert to Gear plugins. Also modified CMakeLists.txt to set CMAKE_INSTALL_PREFIX to source dir as before, rather than /usr