[WIP] Added More Phpdoc Fixers

TODO:
* [x] Added phpdoc_seperation
* [x] Fix the behaviour with some annotations like the phpunit ones - introduced a tag class
* [x] Refactor the docblock classes to model the situation more clearly
* [x] Add tests for the `Tag` class
* [x] Add tests for the `DocBlock` class
* [x] Added phpdoc_order
* [x] Perform regression testing on league/flysystem
* [x] Based on results from testing, make improvements
* [x] Add phpdoc_var fixer
* [x] Perform regression testing on symfony/symfony
* [x] Based on results from testing, make improvements, add more test cases
* [x] Move the phpdoc_order fixer to contrib level
* [x] Add a phpdoc_trim fixer at symfony level, partly taken from phpdoc_separation
* [x] Added phpdoc_no_return_void
* [x] Review fixer orders
* [x] Perform regression testing on guzzle/guzzle
* [x] `@see`, `@link`, `@deprecated`, `@since`, `@author`, `@copyright`, and `@license` annotations should be kept together rather than forced apart by the separation fixer
* [ ] Support annotations with descriptions including bank lines
* [x] Perform regression testing on doctrine/common
* [ ] Perform regression testing on guzzle/guzzle and symfony/symfony again
* [ ] Fix more bugs, and add more test cases
* [ ] Add missing `DocBlock` class tests
* [ ] Add tests for the `Line` class
* [ ] Add tests for the `Annotation` class
* [ ] Discuss fixer names
* [ ] Request another review by @keradus
* [ ] Apply changes
* [ ] Further reviews?

Shall I sort the list alphabetically in the phpunit file (ie, put it above the general line)?