- updated versions and release notes

- howto with steps for preparing a new DD4hep release

--This line, and thowith steps se below, will be ignored--

A    doc/prepare_a_release.howto

   for release v00-08 and v00-09
   ( both have the wrong version number for the libraries 0.7 !)

Improved version of MC particle handler, fix calorimeter hit aggregation with multiple contributions

 - increased version number to v00-07

Change options _WITH_ to _USE_
Print Warning that variables with _WITH_ are deprecated
Change Defintions to _USE_ as well
Add REQUIRED to find_package geant4 and xercesc if they are turned on
Updated documentation
Updated ILDExDet example

    - renamed namespace tgeo to dd4hep
       -> users need to replace tgeo::mm by dd4hep::mm

    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

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

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

  - 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

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