initialisation of images

[tbaudier]

With this commits : a9c5284 we have a new warning with ActorImage (eg: source/test035a)

Dispatching simulation to subprocess ...
Simulation: create RunManager (single thread)
Simulation: initialize Geometry
Simulation: initialize Physics
Simulation: initialize Sources
Simulation: initialize Auxiliary attributes
Simulation: initialize Actors
⚠️ The itk_image in ImageVolume 'ct' is None. If this is unexpected, run my_image_volume.load_input_image() first, where my_image_volume is the variable name of the ImageVolume in your script. 
⚠️ The itk_image in ImageVolume 'ct' is None. If this is unexpected, run my_image_volume.load_input_image() first, where my_image_volume is the variable name of the ImageVolume in your script. 
Simulation: initialize G4RunManager
Simulation: initialize PhysicsEngine
Simulation: initialize Actor-Source links
Simulation: register Actions of actors
Simulation: register Actions of auxiliary attributes
Simulation: check volumes overlap
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Simulation: START (in a new process) (around 90165 events expected)