drop_dense              Internal function to prune quantiles of
                        non-important values for visualization.
qq                      Creates a Q-Q plot
qqchisq1                Creates a Q-Q plot from chi-squared statistics
qqlog                   Creates a Q-Q plot from pre-computed
                        -log10(p-values)
qqnorm                  Creates a Q-Q plot for comparing with normal
                        quantiles
qqplot                  Creates a Q-Q plot
