Update print.php

added the option &bg=1-5 to change the background pattern :)

images go into the same folder as the main pattern 
and they can be found here:
http://forsakenangel.tk/banners/images/pattern1.png
http://forsakenangel.tk/banners/images/pattern2.png
http://forsakenangel.tk/banners/images/pattern3.png
http://forsakenangel.tk/banners/images/pattern4.png
http://forsakenangel.tk/banners/images/pattern5.png