bayesplot v1.3.0

Release notes

(GitHub issue/PR numbers in parentheses)

The biggest change is:

• bayesplot::theme_default is now set as the default ggplot2 plotting theme
  when bayesplot is loaded instead of hardcoded for each plot. This makes
  changing the default theme using ggplot2::theme_set possible.
  Thanks to @gavinsimpson. (#87)

Some minor changes:

• mcmc_hist and mcmc_hist_by_chain now take a freq argument that defaults
  to TRUE (behavior is like freq argument to R's hist function).
• Using a ts object for y in PPC plots no longer results in an error. Thanks
  to @helske. (#94)
• mcmc_intervals doesn't use round lineends anymore as they slightly
  exaggerate the width of the intervals. Thanks to @tjmahr. (#96)