File_Structure_Test to make sure we don't regress.
According to the PHP docs, the "public" keyword is implied on static
functions, so remove it. Also, require private static functions to
start with an _.
http://php.net/manual/en/language.oop5.visibility.php
1) they now have their own matching severity constants
2) they both have convenience functions success(), info(), warning() and error()
3) they both have severity_class()
