v3.2.0

• r(), rcmd() and rscript() can now redirect the standard error of
  the subprocess its standard output. This allows to keep them correctly
  interleaved. For this, you need to either set the stderr argument to
  the special string "2>&1", or to the same output file as specified
  for stdout.

• r(), rcmd() and rscript() now pass ... arguments to
  processx::run(). r_bg() and rcmd_bg() pass ... arguments to
  the processx::process constructor. For r_process, rcmd_process
  and rscript_process extra arguments can be specified as options$extra,
  these are also passed to the processx::process constructor (#100).