Steath loading

This merge request includes previous merge request #74 and changes in xdebug loading behavior. Feel free to integrate this in the next major version.

Extension loading scheme was changed from zend_extension to just extension and then it 'goes up' to a zend extension. It is based in suhosin stealth behavior to defeat closed source zend extensions such as ioncube and zend optimizer.

If you intend to apply this 'stealth' code I think you should speak to Steffan Esser regarding if you can use it or not as I am not sure of Suhosin licensing.

Thanks in advance.