b64 : urlsafe base64 encode / decode

→ tests/main.rs

```rust use ub64::{b64u64, b64d, b64e, u64b64};

[test]

fn main() { let bin = [1, 2, 3]; let b64 = b64e(bin); dbg!(&b64); dbg!(b64d(b64).unwrap()); let n = 9876543210; let u64b64 = u64b64(n); dbg!(&u64b64); dbg!(b64u64(u64_b64)); } ```

run

→ out.txt

txt