Colon Builder

Build structure from colon separate fields like name:colon builder hobbies: book,game,football TV: once a while Sample code ```rust

[derive(ColonBuilder)]

struct Person { #[cb(require)] name: String, hobbies: Vec, #[cb(abbr="TV")] favoriteTVShows: Option }

let p = Person::from_str("name:lu\nTV:show");

```

cargo expand --test test_builder to expand the test file test_builder.rs

TODO

[ ] support 'require' mark