v0.5.1

Changelog:

• Add support for handlebars templating engine.
• Support custom pre out dir name.
• Warn user if output dir already exists.
• Add support for quiet mode (--quiet).
• bug fix: empty --out still treated as empty ./ path.
• bug fix: quiet mode still asking.
• Upgrade rustyline.
• Upgrade Rust edition to 2021.
• bug fix: pre_params overwritten by new_params.