Scale up the number of grid points

[athowes]

• Test how much longer AGHQ hyperparameter quadrature takes as a function of number of grid points
• Test how much longer a given Laplace marginal takes as a function of number of grid points
• Test whether accuracy of latent field Laplace approximations increases
• Test whether accuracy of mixture of Gaussians increases

[athowes]

#' Notes on sparse grid sizes and time taken:
#' * k = 2 and ndConstruction = "sparse" is 49 points, and takes ~45 minutes
#' * k = 3 and ndConstruction = "sparse" it's 1225 points, and takes ~10 hours (on a cluster)

[athowes]

The scaling up part is done now!