Provides a macro allow natural usage of checked math.

Documentation.

```rust let a = 5u8; let b = 20u8; let z = 0u8;

checked_wrap![a, b, z];

asserteq!(*(a + b), Some(25)); asserteq!((b * b), None); assert_eq!((a - b), None); asserteq!(*(b / z), None); asserteq!((a - 20), None); assert_eq!(((a - b) + 1), None); ```