Use tokenizer for inserting child class

With this change we can work with AspectMock & Yii.

Also, constructions like this:
```php
<?php

class Classname {
    public function autoload($class) {
        include $class . '.php';
    }
}

spl_autoload_register(array('Classname', 'autoload'));
```
now processed successfully (before that patch we get a fatal error - because ```Classname``` was replaced with ```Classname__AopProxied``` and ```Classname``` definition appended to the end of file, after ```spl_autoload_register```)