ruc 4.2.0

Rust Util Collections
Documentation
# Change log

#### v4.x

- Add new moduler: hash
- Add new feature: `no_std`

#### v3.x

- Add support for remote command execution based on the SSH protocol
- Remove syntactic sugar for printing information in the 'Debug' format
    - eg, `d!(@a_struct)` should be replaced with `d!("{:?}", a_struct)` in v3.0.x
- Optimize documentations