Reworked external build to allow developers to use it.
Correct version of dcmtk.
Add an option for ITK-4.
Implement the USE_SYSTEM_XXX.
Avoid building dtk Composer when QtDeclarative is not present.
Improve QtDeclarative detection.
Improve QtDeclarative detection.
Remove vtkInria3D subproject, now that it's merged into medInria-plugins