Update paypal_ipn.php

I added a safer way to split $res string from PayPal response.
Example works with IPN Simulator but not with a VALID response from PayPal.
Update paypal_ipn.php

Added split with explode limit.
Update paypal_ipn.php

@JasonZiaja removed the two lines in DEBUG, i already noticed that were not correctly positioned when i developed my IPN script.

Improved my code when the $res gets splitted. It should be nice now.
Changed lines

Changed code for pull request.
Merge pull request #23 from MarioVillani/patch-1

Update paypal_ipn.php