- implemented for the VXD

   Gear objects from DetElements with 
   data structures holding relevant information
   

 - fixed relative pathes to pictures and manuals in
   Doxygen main page

   a DDG4 based simulation with xml configuration files
   (originally in DDSim)
 - renamed print_materials.cc to print_materials.cpp

   - don't write particles created in calo
     unless scattered back into tracker)
   - don't write particles created in tracker
     if below MinimalKineticEnergy ( Geant4ParticleHandler)

 - fixed generator status: set to 0 if
   particle created in simulation

small bug fix for older compilers/os by Frank Gaede: pow(x,x) function is ambiguous with implicit conversion