Reserved Keywords / Forbidden Names detection

[llaville]

Thanks to @fabiang to introduces the first report to add a sniff new reserved words in PHP 7.

This one will complete detection with all other forbidden names :

• https://www.php.net/manual/en/reserved.keywords.php

[llaville]

Differed to next Major version 6.0, because AST could not catch it easily, while it is possible with tokens.

v6.0 will accept either tokens sniff or ast sniff, but v5.4 will be only accept ast sniff.