[C++/BF] fixing for singularities in beta and gamma priors
[C++/BF] fixing for singularities in beta and gamma priors

esc/Psignifit-3.x,esc/Psignifit-3.x,esc/Psignifit-3.x,esc/Psignifit-3.x,esc/Psignifit-3.x,esc/Psignifit-3.x