JMailHelper:isEmailAddress checked the IPv4 and IPv6 address in the domain

I realized that IPs are not entirely correct validating, for example:

```php
<?php
$domain = '192.23.243.23.2';
$regex = '/^[0-9\.]+$/';
preg_match($regex, $domain);
//TRUE
```
One option is to change the regular expression to catch four numbers separated by a dot:

```php
<?php
$domain = '192.23.243.23.2';
$regex = '/^([0-9]{1,3}\.){3}[1-9]+$/';
preg_match($regex, $domain);
//FALSE
```
Another problem is that soon there will be more IPv6 addresses so we would have to change the regular expression to something like:

```php
<?php
$regex = '/^(([0-9]{1,3}\.){3}[1-9]+)|([0-9a-f]*::[0-9]+)$/';
```

Fortunately **PHP5** has a function ([inet_pton](http://php.net/manual/en/function.inet-pton.php)) that returns false if the **IP** address is wrong, I think this is a better solution.

What do you think?