[DRAFT, WIP] PSR-5: PHPDoc Standard

This PR represents the current state of affairs with the PHPDoc Standard. Until this description and subject is altered this PR is considered a Work in Progress and not ready for a final review.

All feedback is welcome, please direct this to the PHP-FIG mailing list to prevent noise in this PR. This PSR covers so many subjects that unless the discussions are separated by topic that it will probably be quite impossible to follow in this PR.

I would also request that people open a thread per issue they would like to discuss and not combine several issues in a single mail; this will help to keep noise-levels down in discussions and for me to loook back or filter important information.

TODO items are tracked in the issue tracker for this PSR: https://github.com/phpDocumentor/fig-standards/issues
There is case when `@method` is used to redefine parent method's return type (I heard you said 'This is not what `@method` was intended for originally', but still). And if parent method is static, some IDEs (i.e. PhpStorm) will mark tag as error with a message like 'Cannot make static method non static'. There is workaround like using `static` keyword in description, but maybe we should add `static` as an optional part of tag?

`@method [static] [return type] [name]([type] [parameter], [...]) [description]`