WIP: tzf's Rust port.

Usage

Add to Cargo.toml

toml tzf-rs = "0.1.2"

```rust use tzf_rs::DefaultFinder;

fn main() { let finder = DefaultFinder::new();

print!("{:?}\n", finder.get_tz_name(116.3883, 39.9289));

} ```

References:

• Documents: https://docs.rs/tzf-rs
• Original Go repo: https://github.com/ringsaturn/tzf
• Binary timezone data: https://github.com/ringsaturn/tzf-rel
• Geometry: use https://github.com/ringsaturn/geometry-rs which is https://github.com/tidwall/geometry's Rust port.