4.3

Pull request for 4.3.

4.3: [![Build Status](https://travis-ci.org/mnapoli/PHP-DI.svg?branch=4.3)](https://travis-ci.org/mnapoli/PHP-DI) [![Coverage Status](https://coveralls.io/repos/mnapoli/PHP-DI/badge.png?branch=4.3)](https://coveralls.io/r/mnapoli/PHP-DI?branch=4.3) [![Scrutinizer Code Quality](https://scrutinizer-ci.com/g/mnapoli/PHP-DI/badges/quality-score.png?b=4.3)](https://scrutinizer-ci.com/g/mnapoli/PHP-DI/?branch=4.3)

master: [![Build Status](https://travis-ci.org/mnapoli/PHP-DI.svg?branch=master)](https://travis-ci.org/mnapoli/PHP-DI) [![Coverage Status](https://coveralls.io/repos/mnapoli/PHP-DI/badge.png?branch=master)](https://coveralls.io/r/mnapoli/PHP-DI?branch=master) [![Scrutinizer Code Quality](https://scrutinizer-ci.com/g/mnapoli/PHP-DI/badges/quality-score.png?b=master)](https://scrutinizer-ci.com/g/mnapoli/PHP-DI/?branch=master)

Tickets:

- [x] #176 New definition type for reading environment variables: `DI\env()`
- [x] #173 `Container::call()` resolves array callables using the class name
- [x] Documentation for #176 (`DI\env()`)
- [x] #181 Auto-register `DI\FactoryInterface` and `DI\InvokerInterface`
- [x] News entry
- [x] Change log