Newtype offering some utility methods for zero-based indices

In order to keep the lengths of method names reasonable, several abbreviations have been used, namely * len for length; * intvl for interval; * int for integer.

Examples

Base case

``` use zerobasedindex::ZeroBasedIndex;

let zbi = ZeroBasedIndex::(2); asserteq!(zbi.trygetlenofclosedintintvlfrom_0(), Some(3)); ```

Base case with zero_based_index::AsZeroBasedIndex

``` use zerobasedindex::{ZeroBasedIndex, AsZeroBasedIndex};

let zbi = 2.aszerobasedindex(); asserteq!(zbi.trygetlenofclosedintintvlfrom0(), Some(3)); ```

Corner case

``` use zerobasedindex::ZeroBasedIndex;

let zbi = ZeroBasedIndex::(usize::MAX); asserteq!(zbi.trygetlenofclosedintintvlfrom_0(), None); ```

Unchecked math

With unchecked_math feature, one can also get access to unsafe superpowers.

License

<sup>Licensed under either of Apache License, Version 2.0 or MIT license at your option.</sup>

<sub>Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this crate by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.</sub>