Replace glasso with glassoFast

[mikemartinez99]

Since graphical lasso does not support multithreading safely as mentioned in #70 , I replaced instances of glasso with glassoFast for some moderate speed increases. While the difference is not too extreme, it did shave ~1 hour off my connection calculation time.

In run_cicero.R, I added a wrapper function called cicero_glasso_fast that takes as input a covariate matrix, rho matrix and a threshold (ridge term) value. All arguments are synonymous to the original glasso function.

cicero_glasso_fast <- function(cov_mat, rho_mat, thr = 1e-4) {
  out <- glassoFast::glassoFast(cov_mat,
                                rho_mat,
                                thr = thr)   # keep quiet

  # Convert the output list to the naming convention that Cicero expects.
  #   out$Theta  -> w
  #   out$W      -> wi
  list(w  = out$w,
       wi = out$wi)
}

Then, functions that originally called glasso instead call the wrapper function:
Functions where glasso was replaced:

find_distance_parameter and generate_cicero_models