Added support for vector parameters in segmentations (int, float, double, string) which are simply space separated values in the xml element
Added TiledLayerSegmentation as an example for a complex segmentation that is calculated based on a volume ID

   - only build if DD4HEP_WITH_GEAR=1

  - fixed  geometry in ILDExVXD_geo.cpp, ILDExTPCSIT_geo.cpp
     wrt. to position of support ans sensitive ladders
  - added test_convert_ild_gear 
  - updated release notes

 -  new wrapper object GearHandler that can be used
    to add GearParametersImpl objects as extension
    to DetElements
 - factory method createGearMgr( LCDD& lcdd )
 - simple program convertToGear
 - so far only TPCParameters added to ILDExDet...

    (renamed ILD converter tests)

  - fixed env scripts
  - increased version to v00-06
  - updated documentation

   - in particular CLHEP is now added to the library path
     if geant4 was built with external CLHEP