Rewrite regex string generator in php

Author: xPaw

CONTRIBUTING.md

@@ -55,6 +55,5 @@ Also note that we are not particularly interested in maintaining rules for engin
 
 If you have PHP installed locally, you can run the tests from the root directory by typing `php tests/Test.php`.
 
-If you also have NodeJS installed locally, you can run `php tests/GenerateTestStrings.php`, and it will
-try to generate test strings that match would match your regex. If you do, make sure to review the test file,
-as for things like `.+` it may generate a lot of fluff.
+Run `php tests/GenerateTestStrings.php`, to generate test strings that match would match your regex.
+This script will automatically execute `Test.php` after generating new strings.