Changing shocks' distribution using simult.m

[jpfeifer]

See

Stochastic Simulation based on Non-Normal Shocks

The problem is not really that Dynare does only support normally distributed shocks but that perturbation is used to solve the models and up to first order, only the mean and the variance of the shock distribution play a role. Thus, even a beta distribution is effectively approximated with a normal distribution for computing the model solution, because the distribution is fully characterized by its first two moments. A limitation of Dynare currently is that it does not allow for skewed distribut…