IDDecoder is now independent of Readout object, instead it finds the correct readout based on the cellID / position

   - to be done: the classes describing the detectors

    - implemented copy c'tor for DetElements
    - fixed memory handling
 - fixed bug in DetectorSurfaces with 
   multiple adding of the same extensions to 
   a DetElement
 - implement gear for EcalBarrel (using DDRec::Calorimeter)

Remove debugging items from CLICSiD compact xml. First implementation of Multipole magnetic field description. Add missing units in DDG4 LCIO conversion.

 - fill for HcalBarrel in createGearForILD

First implementation of dipole field, HepMC reader for DDG4 and fix to import constants into DDG4 python

 - implemented for VXDSupportMaterial using 
   MaterialManager::createAveragedMaterial()

 - added creation of BeamPipe Gear paramaters

   for 'static const int' defined in gear header file 

 - added treatment of gear::FTDParameters (for ILD )