* Update happen during calculation time

 - optional token, keeping retrocompatibility
 - allow to use "beam" at rest as source for gamma cascade

+ Update trapezoid geometry for gaspard

* SIlicon scorer

  - Now follow the new logique
  - Less file
  - Updated geometry

  detector

+ ongoing work for adapting GaspardTrackerAnnular to the new
  scorer scheme

  - A specific bug was present in ThinSi.cc : deletion of the material
    (forbidden)
  - A general bug was present causing the TTree to crash: The branches
    address need to be cleared and the branches deleted before
    reloading the geometry

  - Reload the current generator
  - Load a different one
  - Adding corresponding button in the GUI

 - Delete the actual geometry
 - Clear the Detector Manager
 - Reload Geometry file

For this to work a couple of thing has been done:
 - InitializeRootInput now need an extra SetBranchAddress to tell the
   tree that the previous address is no longer in use
 - Scorer can not be cleared, so need to be retrieved in case of a
   reloading. If they do not exist they are created
 - This is done using the new CheckScorer static method from VDetector

* editing the NPSimulation UI for nicer interface
 - adding menue and icon for common command
 - adding free icons for nice interface

* Adding creation of small sample cube by the material manager to ensure
* every declared material are used, so no crash when writting the DEDX
* tables