cannot adjust adapt_delta or max_treedepth in function atsar::fit_stan(). Allow option to pass through a control list item to mcmc_list.

[dantonnoriega]

Part of what leads fit_stan (R/fit_stan.R) to fail at times is that the default adapt_delta is too large (0.8).

But there is no option to pass a controls option to the mcmc_list variable. I think this is a pretty critical feature to have.

I'll tinker with those over the break and be more specific.