Follow up "Ported TMVATransform to TMVA.h"
Even though the MVA functor is able to load and use TMVA (see !2588 (merged)), it cannot access children information with the CHILD
functor. This is important since MVA algorithms usually mix information from the whole decay, not just the head.
As an example, the inclusive radiative lines cannot implement their MVA using ThOr functors until v2 particles adds children