Fixed

• Fixes regression introduced in 1.19.0 where using an ActionFunc as
  the Action for a command would cause it to error rather than calling the
  function. Should not have a affected declarative cases using func(c *cli.Context) err).
• Shell completion now handles the case where the user specifies
  --generate-bash-completion immediately after a flag that takes an argument.
  Previously it call the application with --generate-bash-completion as the
  flag value.