[ticket/9715] Better email regex

Using email regex created by James Watts and Francisco Jose Martin Moreno.
This passes many more tests for RFC valid emails.

PHPBB3-9715

phpBB/includes/functions.php

@@ -3355,7 +3355,9 @@ function get_preg_expression($mode)
 	switch ($mode)
 	{
 		case 'email':
-			return '(?:[a-z0-9\'\.\-_\+\|]++|&)+@[a-z0-9\-]+\.(?:[a-z0-9\-]+\.)*[a-z]+';
+			// Regex written by James Watts and Francisco Jose Martin Moreno
+			// http://fightingforalostcause.net/misc/2006/compare-email-regex.php
+			return '([\w\!\#$\%\&\'\*\+\-\/\=\?\^\`{\|\}\~]+\.)*(?:[\w\!\#$\%\'\*\+\-\/\=\?\^\`{\|\}\~]|&)+@((((([a-z0-9]{1}[a-z0-9\-]{0,62}[a-z0-9]{1})|[a-z])\.)+[a-z]{2,6})|(\d{1,3}\.){3}\d{1,3}(\:\d{1,5})?)';
 		break;
 
 		case 'bbcode_htm':