for cylindrical surfaces

     virtual Vector2D globalToLocal( const Vector3D& point) const ;
     virtual Vector3D localToGlobal( const Vector2D& point) const ;
 - implementation in VolSurface/Surface for planes
 - added simple tests in  test_surface
 - to be done: cylinders ...

					-- Compuzius

include/DDSurfaces/Vector3D.h:212:11: error: ‘fabs’ is not a member of ‘std’

  - changed ISurface interface for u(),v(),normal() to return Vector3D 
    rather than const Vector3d&
  - added some documentation for Surface methods

   - GEAR is now only used if DD4HEP_WITH_GEAR is true

    to MaterialManager

  - improved utility print_materials to print material properties along  
    a straight line between two points including integrated radiation and 
    interaction lengths (useful for debugging geometries and materials)

  - use averaged material for Surfaces where the thickness extends
    beyond the volume

  - added release notes for material stuff

   - to be used for averaging materials for tracking
     surfaces ...
     

   a non-const double* as argument for TGeoShape::Contains()
   using const_cast<double*> 

 - added simple utility print_materials.cc 
 - started to implement averaging materials for surfaces
    - issue with ILDExDet geometry and assemblies ...

   - use in DDRec::SurfaceMaterial
 - added explicit method double * const_array() to  DDSurfaces::Vector3D
   in order to fix issue  with conversion operator that is not 
   recognized by some compilers

 - added DDSurfaces to Doxygen
 - cleaned up DDSurfaces to have only 
   pure abstract base classes (interfaces)

   - no superseeded by pure abstract ISurface and IMaterial

     - draw sensitive surfaces in red and helper surfaces in gray
     - protect against missing lcio input file
  - reduced printout from VolumeManager  (changed INFO to DEBUG)

   access to cylinider radius for the tracking

   as this causes template lookup errors on some machines :
   -> use explicit conversion with to<T>() instead

     to provide some hierarchical strucutre to the geometry

   ( copy did not work ) 

    - ILD examples for now include internal header DetectorInterna.h
  - minor fixes for printing ISurfaces
  - added drawing of z-planes inside tubes (TPC endcap)
  - tried to add copy c'tor foe extension object VolSurfaceList
     -> causes seg. fault ...
     

Hopefully I got the assemblies right now. Assembly test added in examples/ClientTests. Please see also doc/release.notes