Change &null; from NULL to null, etc.

Hi! Since a long time there is a patch from Marco Pivetta in the online editor suggesting to change some initializers from &null; to null, and I wonder if we should change the definition of the entities &null;, &false; and &true; from upper case to lower case. While constants are usually written all upper case, these three reserved words are commonly spelled in lower case, what is required by PSR-2[1] and the PEAR coding standards[2]. Thoughts? [1] <http://www.php-fig.org/psr/psr-2/#2-5-keywords-and-true-false-null> [2] <https://pear.php.net/manual/en/standards.naming.php> -- Christoph M. Becker