v3.1.0

• New rscript() function and rscript_process class to execute
  R scripts via Rscript (#40, #81).

• Library paths are now correctly set up for system() (and similar)
  calls from the callr subprocesses (#83, #84).

• Pass options("repos") to the child process as is, without checking.
  Closes #82.

• r_session$run_with_output() now returns an S3 object with class
  callr_session_result.

• r_session$run*() handle interrupts properly. It tries to interrupt
  the background process fist, kills it if it is not interruptable,
  and then re-throws the interrupt condition, going back to the top level
  prompt if the re-thrown condition is un-caught.

v3.0.0

• New r_session class: a background R session you can send commands to
  (#56).

• Rewrote passing the library path to the subprocess (#73, #75)

• Retain names of the repos option (#67, @jennybc)

callr 2.0.4

• pkgdown web site at https://callr.r-lib.org (#52, #53).

• callr users .Renviron files now (and R_ENVIRON_USER as well),
  but overrides the library path, as requested in r(), etc. (#30).

• callr now handles the case when the subprocess calls quit().

• callr now uses the processx package, instead of embedded code,
  to create and control processes.