Extracts summarised parameter posteriors from a stanfit object using rstan::summary() in a format consistent with other summary functions in {EpiNow2}.
params: A character vector of parameters to extract. Defaults to all parameters.
CrIs: Numeric vector of credible intervals to calculate.
var_names: Logical defaults to FALSE. Should variables be named. Automatically set to TRUE if multiple parameters are to be extracted.
Returns
A <data.table> summarising parameter posteriors. Contains a following variables: variable, mean, mean_se, sd, median, and lower_, upper_ followed by credible interval labels indicating the credible intervals present.