This function will locate and extract the the distributions for Bayesian priors and random parameters as specified in the design. The output is used to create the matrix of correct draws for priors and parameters.
A single character string or list of character strings with a single or multiple utility functions
A string indicating the type: prior or param
A named vector of priors or parameters where the type of distribution is given by a character letter: "normal", "lognormal", "uniform" or "triangular"
IMPORTANT: The function will silently drop duplicates.