DataStreamPtr version of setGeometry methods

For creating zones with "world geometry" (terrain) it takes a file name. For Ogre's main scene managers you can use DataStreamPtr to better control where that data comes from. I think it would be a lot more flexible if similar functions were added for PCZSceneManager and PCZone. I can do this, but I didn't want to make changes without letting you know first.

That's a good idea Praetor. Submit a patch and I'll see about getting it in.