fixed python bindings includes: Z3_Context was renamed to Z3_Backend
fixed python bindings includes: Z3_Context was renamed to Z3_Backend

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