fixed memory leaks of UTreeEvaluator by using shared_ptr
fixed memory leaks of UTreeEvaluator by using shared_ptr

agra-uni-bremen/metaSMT,hoangmle/metaSMT,finnhaedicke/metaSMT,agra-uni-bremen/metaSMT,finnhaedicke/metaSMT,hoangmle/metaSMT,nbruns1/metaSMT,agra-uni-bremen/metaSMT,hoangmle/metaSMT,nbruns1/metaSMT,nbruns1/metaSMT,finnhaedicke/metaSMT