rlang 0.4.7

• cnd_muffle() now returns FALSE instead of failing if the
  condition is not mufflable (#1022).

• warn() and inform() gain a .frequency argument to control how
  frequently the warning or message should be displayed.

• New raw_deparse_str() function for converting a raw vector into a
  string of hexadecimal characters (@krlmlr, #978).

• The backtraces of chained errors are no longer decomposed by error
  context. Instead, the error messages are displayed as a tree to
  reflect the error ancestry, and the deepest backtrace in the ancestry
  is displayed.

  This change simplifies the display (#851) and makes it possible to
  rethow errors from a calling handler rather than an exiting handler,
  which we now think is more appropriate because it allows users to
  recover() into the error.

• env_bind(), env_bind_active(), env_bind_lazy(), env_get(),
  and env_get_list() have been rewritten in C.

• env_poke() now supports zap() sentinels for removing bindings
  (#1012) and has better support for characters that are not
  representable in the local encoding.

• env_poke() has been rewritten in C for performance.

• The unicode translation warnings that appeared on Windows with R 4.0
  are now fixed.

• env_unbind(inherit = TRUE) now only removes a binding from the
  first parent environment that has a binding. It used to remove the
  bindings from the whole ancestry. The new behaviour doesn't
  guarantee that a scope doesn't have a binding but it is safer.

• env_has() is now rewritten in C for performance.

• dots_list() gains a .named argument for auto-naming dots (#957).

• It is now possible to subset the .data pronoun with quosured
  symbols or strings (#807).

• Expressions like quote(list("a b" = 1)) are now properly deparsed
  by expr_deparse() (#950).

• parse_exprs() now preserves names (#808). When a single string
  produces multiple expressions, the names may be useful to figure out
  what input produced which expression.

• parse_exprs() now supports empty expressions (#954).

• list2(!!!x) no longer evaluates x multiple times (#981).

• is_installed() now properly handles a pkg argument of length > 1.
  Before this it silently tested the first element of pkg only
  and thus always returned TRUE if the first package was installed
  regardless of the actual length of pkg. (#991, @salim-b)

• arg_match0() is a faster version of arg_match() for use when performance
  is at a premium (#997, @krlmlr).