=> demonstrates bug with signed encoder fields:
        <id>system:5,side:-2,layer:9,module:8,sensor:8</id>   
   leads to duplicate volumes 
         <id>system:5,side:2,layer:9,module:8,sensor:8</id>
   does not !

   error message when exception is not caught ...
   ( also creates ROOT seg fault and stack trace
     which might be useful for debugging - 
     don't call exit(1) to avoid seg fault 
     in lcdd_unexpected() )

   -D DD4HEP_USE_LCIO=1 ( -D LCIO_DIR=_lcio_install_dir_ )
     - LCIO_DIR is not needed when iLCSoft is initialized

   -D DD4HEP_USE_BOOST -D BOOST_ROOT=_path_to_boost_
 - client packages will automatically also use boost
   ( add_definition( DD4HEP_USE_BOOST ))

   -D DD4HEP_USE_BOOST -D BOOST_ROOT=_path_to_boost_
 - client packages will automatically also use boost 
   ( add_definition( DD4HEP_USE_BOOST )) 
   

      build all examples in one go
    - made necessary changes in package cmake files
      for this to work
    - updated documentation in Readme

   -> already in $DD4HEP_LIBRARIES

     Property& operator=(const std::string& val);
   as this is in conflict with explicit instantiation (using string) of:
     template <typename TYPE> Property& operator=(const TYPE& val);
  
   -> Need checking with other compilers !!