Renames the columns of x_j from terms to parameters, so that a generic
parameter is a single column even if its attribute has a different name in
each alternative. Parameters that do not enter the utility function of an
alternative are zero for that alternative. The columns are ordered as the
priors, which ensures that the variance-covariance matrix derived by
derive_vcov matches the priors.
align_x_j(x_j, terms, names_priors)A list of model matrices returned by define_x_j
A list of terms and their parameters returned by
pair_param_terms
The names of the priors
The list x_j with one column per prior in the order of the priors