u256-literal 1.2.0

Procedural macro for converting u256 literals to U256 at compile time.
Documentation 
# Changelog
All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

## 1.2.0 (2022-07-22)
### Added
- Support solidity like expression as `1e18`.

## 0.1.0 (2021-06-17)
### Added
- Initial implementation of `u256!()` macro.