* **Breaking changes: References have changed behaviour** * `Reference` doesn't extend `Firebase` anymore and has changed behaviour (see the [doc/02-references.md](documentation about References)). * Reference data can be accessed with `$reference->getData()`, which returns an array, or directly with `$reference['key']`. * Reference data can be updated with `$reference->update(['key' => 'value'])` or with `$reference['key'] = 'value'`. * Improved test coverage. * Added Makefile to ease test execution. * Extended documentation and moved in to the doc folder.