Created caching Behavior for "*.obj" loader (loaders/Obj.java). Now
loading twice or more the same mesh will cause the next instance to
share the mesh buffer, face, vertex, normals and texCoord data.
This saves a lot of memory, and also has positive impact on performance.


Changed scaling behavior - now the mesh is not recreated.

This is due to caching in Obj loader which creates instances of meshes,
which share the mesh buffer. Recreating the buffer every time a mesh was
loaded was eating a lot of memory. Also recreating the mesh buffer when
scaling was not good for memory and performance, now the transformations
include the scale Vector3, which is considered, when:
- Calculating intersection when picking (Pick.java)
- Scaling a node in scene graph (look at Spatial.java - getGlobalScale)

Also the names of Spatial method "getWorld*" were changed to
"getGlobal*" so it wont confuse.

Smaller changes:
-Added Vector3::divide(Vector3)

Had some naming issuess (Camera.java, Scene.java, ... ) - update() vs
align()


Added BigSceneTest - for testing performance in a huge scene.