New Features

--infer lets cargo-play to infer the third-party dependencies used in the source code. No more dull dependency specifications. However, with two catches:
- Under the hood cargo-play finds all the use statements in your code. That means if you directly use some external crates, cargo-play will not be able to recognize such dependency.
- For the same reason, if you use use statements to rename things, cargo-play would incorrectly recognize these as dependencies.
--save=<PATH> generates a Cargo project at <PATH> based on the files passed to cargo-play.
You can now pass flags to your program run by cargo-play. Simply put any flags after -- and these flags will be passed to your program. For example, running cargo play cmd.rs -- --help will be running your program with --help.
--cargo-options=<OPTIONS> allows you to pass flags to the underlying Cargo command cargo-play invokes.
--release allows you to run your program in release mode.

Bugfix

cargo-play is now able to skip shebang and empty lines at the beginning of files correctly. Thanks @norcalli.
cargo-play is now able to generate Cargo.toml correctly when there is mixed git dependency starting with "d". Thanks @reitermarkus.