mvn_sup simulates the distribution of the supremum of the specified
multivariate normal distribution by drawing repeatedly from the multivariate
normal distribution and calculating the maximum of each vector.
mvn_sup(n, mu, Sigma, seed = NULL)mvn_sup returns a vector of suprema of length n.
An integer determining the number of draws from the multivariate normal distribution.
A numeric vector representing the mean of the multivariate normal distribution.
A numeric matrix representing the variance-covariance matrix of the mutlivariate normal distribution.
An integer setting the random seed or NULL if it should
not be set.