v0.4.0

This release is only compatible with Rust 1.31.0 and later.

Added

• The CliResult type alias was added as an easy to write type to be used as an
  return type in main functions. It uses the exitfailure crate internally.

Removed

• The Result type alias has been removed from the prelude.

  To migrate from 0.3, please replace Result<$X> with Result<$X, Error>.

• Structopt is no longer re-exported.

  To migrate from 0.3, please add structopt = "0.2" to your Cargo.toml,
  and add use structopt::StructOpt; to your source files.

• The main! macro has been removed. It was the cause of much confusion and
  was originally introduced to work around the lack of support for using the ?
  operator in the main function.

  To migrate from 0.3, you should use a regular main function like
  fn main() -> CliResult { Ok(()) }. You'll need to return Ok(()) at the
  end to indicate the program was successful.

  To get access to your CLI arguments, use let args = Cli::from_args();
  (adjust the Cli name with the name of your struct that derives StructOpt.)

  To enable logging, it is easiest to add the line
  args.verbosity.setup_env_logger(&env!("CARGO_PKG_NAME"))?; right after the
  previous one loading the CLI arguments. You can also initialize a custom
  logger with the right log level directly by accessing
  args.verbosity.log_level().