made some useful updates

Hi, I made some useful updates, if you like you can pull them in. Cheers!

- changed texture to textureref
- added the ability to send in xmltree when creating the object to make it more flexible when there are multiple instances
- set the default dataformat to xml since there's only one at the moment
- alpha blending is enabled even when no alpha is applied so the edges on transparent png's look smoother.