Enable fixture inheritance
Add @self reference
Clarify code and fix include result comparison, fixes #89
Merge remote-tracking branch 'ChessCom/MD/self-reference'
No need to set to null before unsetting, refs #87
Make last extended template win
Merge pull request #86 from ajessu/fixtures_inheritance

Enable fixture inheritance
Add 5.6 testing
Add built-in identity provider, support for others

- Update README with identity provider info
- Add syntactic sugar for default identity provider (no provider name, ie <(...)> becomes identity<(...)>
Extend the ability to pass references to providers

- Allow non-nested references anywhere within a provider call
- Allow as many of them as you want (as long as they aren't nested)
- Add documentation
- Add test