rlang 0.4.1

• New experimental framework for creating bulleted error messages. See
  ?cnd_message for the motivation and an overwiew of the tools we
  have created to support this approach. In particular, abort() now
  takes character vectors to assemble a bullet list. Elements named
  x are prefixed with a red cross, elements named i are prefixed
  with a blue info symbol, and unnamed elements are prefixed with a
  bullet.

• Capture of backtrace in the context of rethrowing an error from an
  exiting handler has been improved. The tryCatch() context no
  longer leaks in the high-level backtrace.

• Printing an error no longer recommends calling last_trace(),
  unless called from last_error().

• env_clone() no longer recreates active bindings and is now just an
  alias for env2list(as.list(env)). Unlike as.list() which returns
  the active binding function on R < 4.0, the value of active bindings
  is consistently used in all versions.

• The display of rlang errors derived from parent errors has been
  improved. The simplified backtrace (as printed by
  rlang::last_error()) no longer includes the parent errors. On the
  other hand, the full backtrace (as printed by rlang::last_trace())
  now includes the backtraces of the parent errors.

• cnd_signal() has improved support for rlang errors created with
  error_cnd(). It now records a backtrace if there isn't one
  already, and saves the error so it can be inspected with
  rlang::last_error().

• rlang errors are no longer formatted and saved through
  conditionMessage(). This makes it easier to use a
  conditionMessage() method in subclasses created with abort(),
  which is useful to delay expensive generation of error messages
  until display time.

• abort() can now be called without error message. This is useful
  when conditionMessage() is used to generate the message at
  print-time.

• Fixed an infinite loop in eval_tidy(). It occurred when evaluating
  a quosure that inherits from the mask itself.

• env_bind()'s performance has been significantly improved by fixing a bug
  that caused values to be repeatedly looked up by name.

• cnd_muffle() now checks that a restart exists before invoking
  it. The restart might not exist if the condition is signalled with a
  different function (such as stop(warning_cnd)).

• trace_length() returns the number of frames in a backtrace.

• Added internal utility cnd_entrace() to add a backtrace to a
  condition.

• rlang::last_error() backtraces are no longer displayed in red.

• x %|% y now also works when y is of same length as x (@rcannood, #806).

• Empty named lists are now deparsed more explicitly as
  "<named list>".

• Fixed chr() bug causing it to return invisibly.