Feature request: Option for a non-normal likelihoods

Currently, the model specification is that of a normal likelihood. It'd be potentially useful to add options for other likelihoods --- like a lognormal, gamma, or poisson (for unbounded count outcomes). These would give a bit more flexibility in model specification at the user level while mechanically enforcing 0 as a lower bound for the outcome. I imagine that the lognormal would be the most straightforward to implement, but the others would also be useful as roadmap items in the future.