Resolves: #45

* Ass missing colon.

* Update docs, add sniff and test.
* Add first configuration.

Relates: #45

* Allow executing tests for single sniff through phpunit '--filter'.
* Provide structure to add further tests for a single sniff.
* Make output more clear, which sniff was tested.

Relates: #45

* Add docs, sniff, tests.
* Add first configuration.

Relates: #45

* Remove construct from interface.
* Fix wrong type hints.
* Keep naming of variable in sync.
* Also keep conditions format in sync.

Relates: #71

TASK: Document yaml format for features

Closes #76

See merge request !81

Feature/update docs

See merge request !82

* To enable others to configure their own features.

Resolves: #76

* To make writing merge requests easier.
* Also this should keep them in same structure.

* Remove unnecessary docs.
* Add necessary docs.

* Don't duplicate code and logic.
* Move common code to parent class.

Relates: #71

* Adjust CI , composer and docs.
* Migrate modern code to 5.6 supported code.

Relates: #71

* Also migrate RemovedClassFeature to new structure with
  AbstractYamlRemovedUsage

Relates: #71

* Migrate GenericConstantUsageSniff to new architecture.
* Move non common functionality from AbstractGenericPhpUsage to concrete
  classes.

Relates: #71

* Migrate GenericFunctionCallSniff to new architecture.
* Provide new abstract class for php removed functions and constants.
* Fix TypoScriptSniff not always returning array.
* Adjust warnings in Expected.json

Relates: #71

* As PHP 7.1 is required, document and adjust tests in CI.

Relates: #71

* Refactor yaml based removed check architecture.
* Migrate TypoScriptSniff to new architecture.

Relates: #71

* Handle empty yaml files for features in options class.

* Add feature to existing code base and logic, see #72 .
* Add first removed classes for TYPO3 7.0 as example.
* Adjust first test to make sure basic implementation works.

Relates: #41

Feature/54 add checks for typoscript

Closes #54

See merge request !74

Feature/72 refactor sniff architecture

Closes #72

See merge request !78

* Also test that we don't modify working parts

* Reduce indentation.
* Provide internal API to add new feature with necessary checks.

* To keep naming in sync with code, to make examples work.

* As long as we don't make use of intersphinx disable it to speed up
  rendering of documentation.

* Remove unnecessary documentation.
* Remove unused code.
* Add missing documentation.

Relates: #72

Relates: #72